Diagnosis of tuberculosis an Update
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Transcript of Diagnosis of tuberculosis an Update
![Page 1: Diagnosis of tuberculosis an Update](https://reader031.fdocuments.in/reader031/viewer/2022032113/55a62b711a28abd5138b48bb/html5/thumbnails/1.jpg)
Diagnosis of Tuberculosis
an update
DrTVRao MD
DrTVRao MD 1
Testing for TB Infection
bull Tuberculosis (TB) is a disease that is spread through the air from one person to another There are two kinds of tests that are used to determine if a person has been infected with TB bacteria the tuberculin skin test and other direct and indirect Tests
DrTVRao MD 2
Diagnosis of TB Disease
bull People suspected of having TB disease should be referred for a medical evaluation which will include
Medical history Physical examination
Test for TB infection (TB skin test or TB blood test)
bull Chest radiograph (X-ray) and
bull Appropriate laboratory tests
DrTVRao MD 3
Who Should Get Tested for TB
bull TB tests are generally not needed for people with a low risk of infection with TB bacteria
bull Certain people should be tested for TB bacteria because they are more likely to get TB disease including
bull People who have spent time with someone who has TB disease People with HIV infection or another medical problem that weakens the immune system
bull People who have symptoms of TB disease (fever night sweats cough and weight loss)
DrTVRao MD 4
Who Should Get Tested for TB
bull People who have spent time with someone who has TB disease
bull People with HIV infection or another medical problem that weakens the immune system
bull People who have symptoms of TB disease (fever night sweats cough and weight loss)
DrTVRao MD 5
Who Should Get Tested for TB
bull People from a country where TB disease is common (most countries in Latin America the Caribbean Africa Asia Eastern Europe and Russia)
bull People who live or work somewhere in the United States where TB disease is more common (homeless shelters prison or jails or some nursing homes)
bull People who use illegal drugsDrTVRao MD 6
X ray of Chest a Commonly used Diagnostic tool
bull Acute pulmonary TB can be easily seen on an X-ray However the picture it presents is not specific and a normal chest X-ray cannot exclude extrapulmonary TB Also in countries where resources are more limited there is often a lack of X-ray facilitiesDrTVRao MD 7
Other testsbull Other tests such
as a chest x-ray and a sample of sputum are needed to see whether the person has TB disease
DrTVRao MD 8
Types of specimens-Sputum
- BAL
-Pleural effusions
- Urine
- Stool
-CSF
-Aspiration ( gastric ndash cold abscess)
- Blood in case of haematogenous TB
DrTVRao MD 9
Laboratory Diagnosis
1- Sputum smears stained by Z-N stain
Three morning successive mucopurulent sputum samples are needed to diagnose pulmonary TB
Advantage - cheap ndash rapid
- Easy to perform
- High predictive value gt 90
- Specificity of 98
Disadvantages
- sputum ( need to contain 5000-10000 AFB ml)
- Young children elderly amp HIV infected persons may not produce cavities amp sputum containing AFB
Sputum Collectionbull Sputum specimens
are essential to confirm TBndash Specimens should be
from lung secretions not saliva
bull Collect 3 specimens on 3 different days
bull Spontaneous morning sputum more desirable than induced specimens
bull Collect sputum before treatment is initiated
11
Interpretation of sputum stained by
Z N Stain (WHO )
More than 10 bacilli field ------- +++
From 1 ndash 10 bacilli field ------- ++
From 10 ndash 99 bacilli 100 fields ----- +
From 1 -9 bacilli100 fields ------ write the no
No bacilli seen ---------- negative
2- Detecting AFB by fluorochrome stain using fluorescence microscopy
The smear may be stained by auramine-O dye In this method the TB bacilli are stained yellow against dark background amp easily visualized using florescent microscope
Advantages
- More sensitive
- Rapid
Disadvantages
- Hazards of dye toxicity
- more expensive
- must be confirmed by Z-N stain
Acid Fast Bacilli under Fluorescent Microscope
DrTVRao MD 14
Culturebull Used to confirm
diagnosis of TB
bull Culture all
specimens even if
smear is negative
bull Initial drug isolate
should be used to
determine drug
susceptibility15
Laboratory Diagnosis
1- Sputum smears stained by Z-N stain
Three morning successive mucopurulent sputum samples are needed to diagnose pulmonary TB
Advantage - cheap ndash rapid
- Easy to perform
- High predictive value gt 90
- Specificity of 98
Disadvantages
- sputum ( need to contain 5000-10000 AFB ml)
- Young children elderly amp HIV infected persons may not produce cavities amp sputum containing AFB
DrTVRao MD 16
2- Detecting AFB by fluorochrome stain using fluorescence microscopy
The smear may be stained by aura mine-O dye In this method the TB bacilli are stained yellow against dark background amp easily visualized using florescent microscope
Advantages
- More sensitive
- Rapid
Disadvantages
- Hazards of dye toxicity
- more expensive
- must be confirmed by Z-N stain
DrTVRao MD 17
LowensteinndashJensen mediumbull When grown on LJ
medium M tuberculosis appears as brown granular colonies (sometimes called buff rough and tough) The media must be incubated for a significant length of time usually four weeks due to the slow doubling time of M tuberculosis DrTVRao MD 18
3- Cultures on L J media
Lowenstein ndashJensen medium is an egg based media
with addition of salts 5 glycerol Malachite green
Advantages - Specificity about 99
- More sensitive (need lower no of bacilli 10-100 ml)
- Can differentiate between TB complex amp NTM using biochemical reactions
- Sensitivity tests for antituberculous drugs
( St INH Rif E)
Disadvantages Slowly growing ( up to 8 weeks )DrTVRao MD 19
Recent Methods for Diagnosis
I ndashBACTEC 460 ( rapid radiometric culture system )specimens are cultured in a liquid medium
(Middle brook7H9 broth base )containing C14 ndashlabelled palmitic acid amp PANTA antibiotic mixture
Growing mycobacteria utilize the acid releasing radioactive CO2 which is measured as growth index (GI) in the BACTEC instrument
The daily increase in GI output is directly proportional to the rate amp amount of growth in the medium
Mycobacteria Growth Indicator
Tube (MGIT)
Tube contains modified Middlebrook 7H9
broth base with OADC enrichment amp
PANTA antibiotic mixture
All types of clinical specimens pulmonary
as well as extra-pulmonary ( except
blood) could be cultured on this type of
media
The MGIT 960 System
The MGIT 960 system is a non-radiometeric
automated system that uses the MGIT media amp
sensors to detect the fluorescence
Advantages
-The system holds 960 plastic tubes which are
continuously monitored
- Early detection as the machine monitoring amp
reading the tubes every hour
Detection and identification of mycobacteria directly
from clinical samplesbull Genotypic Methods
bull 1048708 PCR
bull 1048708 LAMP
bull 1048708 TMA NAA
bull 1048708 Ligase chain reaction
bull 1048708 Phenotypic Methods
bull 1048708 FAST Plaque TB
DrTVRao MD 23
bull Essentially PCR is a way to make millions of identical copies of a specific DNA sequence which may be a gene or a part of a gene or simply a stretch of nucleotides with a known DNA sequence the function of which may be unknown
Polymerase Chain Reaction (PCR)
DrTVRao MD 24
Polymerase Chain Reaction (PCR) amp
Gene probeNucleic acid probes amp nucleic acid amplification
tests in which polymerase enzymes are used to
amplify ( make many copies of specific DNA or
RNA sequences extracted from mycobacterial
cells
Advantages
- Rapid procedure - High sensitivity (1-10
( 3 ndash 4 hours) bacilli ml sputum)
bull Interferon-γ assays measure cell-mediated immunity by quantifying IFN-γ released from sensitized T cells in whole bloodPBMCs incubated with TB antigens
Quantiferon-GOLD
DrTVRao MD 26
What Positive Skin Test ( Tuberculin Test means)
bull A positive TB skin test or TB blood test only tells that a person has been infected with TB bacteria It does not tell whether the person has latent TB infection (LTBI) or has progressed to TB disease
DrTVRao MD 27
Tuberculin TestInterpretation A positive test indicates previous exposure and
carriage of TB A negative tuberculin test excludes infection in
suspected persons Tuberculin positive persons may develop
reactivation type of TB Tuberculin negative persons are at risk of gaining
new infection False positive reactions are mainly due to
- Infection with nontuberculous mycobacteria
DrTVRao MD 28
False negative reactions may be due to-
bull False negative reactions may be due to
- Sever tuberculosis infection (Miliary TB) -Hodgkinrsquos disease
bull Corticosteroid therapy - Malnutrition -AIDS
bull Children below 5 years of age with no exposure history
bull Positive test must be regarded suspicious
DrTVRao MD 29
Tuberculin Test( Mantoux Test )
bull Test to be interpreted in relation to clinical evaluation
bull Even the induration of 5 mm to be considered positive when tested on HIV patients
bull Lacks specificity
Positive Test Means
bull This means the personrsquos body was infected with TB bacteria Additional tests are needed to determine if the person has latent TB infection or TB disease A health care worker will then provide treatment as needed
DrTVRao MD 31
Negative Test Means
bull This means the personrsquos body did not react to the test and that latent TB infection or TB disease is not likely
DrTVRao MD 32
Tuberculin Testing - Limitations
bull False positive reactions are mainly due to
bull - Infection with nontuberculous mycobacteria
bull False negative reactions may be due to
bull - Sever tuberculosis infection (Miliary TB) -Hodgkinrsquos disease
bull - Corticosteroid therapy - Malnutrition -AIDS
bull Children below 5 years of age with no exposure history
bull - Positive test must be regarded suspicious DrTVRao MD 33
Recent Methods for Diagnosis
I ndash BACTEC 460 ( rapid radiometric culture system )
Specimens are cultured in a liquid medium (Middle brook7H9 broth base )containing C14 ndash labeled palmitic acid amp PANTA antibiotic mixture
Growing mycobacteria utilize the acid releasing radioactive CO2 which is measured as growth index (GI) in the BACTEC instrument
The daily increase in GI output is directly proportional to the rate amp amount of growth in the medium
DrTVRao MD 34
TB blood testsbull TB blood tests (also called interferon-gamma
release assays or IGRAs) measure how the immune system reacts to the bacteria that cause TB An IGRA measures how strong a personrsquos immune system reacts to TB bacteria by testing the personrsquos blood in a laboratory
bull Two IGRAs are approved by the US Food and Drug Administration (FDA) and are available in the United States
DrTVRao MD 35
Positive IGRAbull This means that the
person has been infected with TB bacteria Additional tests are needed to determine if the person has latent TB infection or TB disease A health care worker will then provide treatment as needed
DrTVRao MD 36
Negative IGRA
bull This means that the personrsquos blood did not react to the test and that latent TB infection or TB disease is not likely
DrTVRao MD 37
IGRAs are the preferred method of TB infection testing for the following
People who have received bacilli ChalmettendashGueacuterin (BCG) BCG is a vaccine for TB disease People who have a difficult time returning for a second appointment to look for a reaction to the TST
There is no problem with repeated IGRAs
DrTVRao MD 38
III Polymerase Chain Reaction
(PCR) amp Gene probeNucleic acid probes amp nucleic acid amplification
tests in which polymerase enzymes are used to
amplify ( make many copies of specific DNA or
RNA sequences extracted from mycobacterial
cells
Advantages
- Rapid procedure - High sensitivity (1-10
( 3 ndash 4 hours) bacilli ml sputum)
DrTVRao MD 39
Molecular DR testing is particularly useful for
bull Patients suspected or at high risk of having drug-resistant TBvery ill patients for whom drug-susceptibility information might alter case management decisions such as patients who do not get better while taking standard first-line therapy
DrTVRao MD 40
Detection of MDR Tuberculosis
bull Very ill patients for whom drug-susceptibility information might alter case management decisions such as patients who do not get better while taking standard first-line therapy
DrTVRao MD 41
Detection of MDR Tuberculosis
bull outbreak or contact investigations when drug resistance is suspected in the source case or in some severely immunocompromised persons such as HIV-infected persons or those receiving dialysis in which knowledge of drug-susceptibility would be a significant benefit and affect preventive therapy decisions
DrTVRao MD 42
Tuberculosis and HIV infection
bull HIV association has become a threat to the developed countries too
bull HIV association will lead to rapid spread of tuberculosis
DrTVRao MD 43
HIV Considerations
bull HIV is the strongest risk factor for progression to active disease
bull HIV kills CD4+ T Helper cells which normally inhibit M tuberculosis
bull HIV interferes with PPD skin test
bull Protease inhibitors interfere with rifampin
DrTVRao MD 44
Epidemiologybull An ancient disease called as white plague
bull 13 of the world population is infected
bull 2 billion infected
bull Each year 9 lakhs to 1 million are infected
bull Poor nations phase the burnt of the disease
bull In developing world gt 4o of the population is effected
bull 15 million suffer the disease
bull 3 million are highly infective
DrTVRao MD 45
MDR tuberculosis
bull Multidrug resistant tuberculosis has become a global threat
bull In 1993 WHO declared Tuberculosis a Global emergency
bull Animals shed the bacilli in Milk humanrsquos get infected after drinking the unsterilized Milk
bull Pasteurization has reduced the incidence of Bovine tuberculosis
DrTVRao MD 46
Why Tuberculosis continues to be Important
bull Someone in the world is newly infected with TB bacilli every second
bull Overall one-third of the worlds population is currently infected with the TB bacillus
bull 5-10 of people who are infected with TB bacilli (but who are not infected with HIV) become sick or infectious at some time during their life People with HIV and TB infection are much more likely to develop TB
DrTVRao MD 47
bull Programme Created by DrTVRao MD for Medical and Paramedical
Students in Developing world
bull Email
bull doctortvraogmailcom
DrTVRao MD 48
![Page 2: Diagnosis of tuberculosis an Update](https://reader031.fdocuments.in/reader031/viewer/2022032113/55a62b711a28abd5138b48bb/html5/thumbnails/2.jpg)
Testing for TB Infection
bull Tuberculosis (TB) is a disease that is spread through the air from one person to another There are two kinds of tests that are used to determine if a person has been infected with TB bacteria the tuberculin skin test and other direct and indirect Tests
DrTVRao MD 2
Diagnosis of TB Disease
bull People suspected of having TB disease should be referred for a medical evaluation which will include
Medical history Physical examination
Test for TB infection (TB skin test or TB blood test)
bull Chest radiograph (X-ray) and
bull Appropriate laboratory tests
DrTVRao MD 3
Who Should Get Tested for TB
bull TB tests are generally not needed for people with a low risk of infection with TB bacteria
bull Certain people should be tested for TB bacteria because they are more likely to get TB disease including
bull People who have spent time with someone who has TB disease People with HIV infection or another medical problem that weakens the immune system
bull People who have symptoms of TB disease (fever night sweats cough and weight loss)
DrTVRao MD 4
Who Should Get Tested for TB
bull People who have spent time with someone who has TB disease
bull People with HIV infection or another medical problem that weakens the immune system
bull People who have symptoms of TB disease (fever night sweats cough and weight loss)
DrTVRao MD 5
Who Should Get Tested for TB
bull People from a country where TB disease is common (most countries in Latin America the Caribbean Africa Asia Eastern Europe and Russia)
bull People who live or work somewhere in the United States where TB disease is more common (homeless shelters prison or jails or some nursing homes)
bull People who use illegal drugsDrTVRao MD 6
X ray of Chest a Commonly used Diagnostic tool
bull Acute pulmonary TB can be easily seen on an X-ray However the picture it presents is not specific and a normal chest X-ray cannot exclude extrapulmonary TB Also in countries where resources are more limited there is often a lack of X-ray facilitiesDrTVRao MD 7
Other testsbull Other tests such
as a chest x-ray and a sample of sputum are needed to see whether the person has TB disease
DrTVRao MD 8
Types of specimens-Sputum
- BAL
-Pleural effusions
- Urine
- Stool
-CSF
-Aspiration ( gastric ndash cold abscess)
- Blood in case of haematogenous TB
DrTVRao MD 9
Laboratory Diagnosis
1- Sputum smears stained by Z-N stain
Three morning successive mucopurulent sputum samples are needed to diagnose pulmonary TB
Advantage - cheap ndash rapid
- Easy to perform
- High predictive value gt 90
- Specificity of 98
Disadvantages
- sputum ( need to contain 5000-10000 AFB ml)
- Young children elderly amp HIV infected persons may not produce cavities amp sputum containing AFB
Sputum Collectionbull Sputum specimens
are essential to confirm TBndash Specimens should be
from lung secretions not saliva
bull Collect 3 specimens on 3 different days
bull Spontaneous morning sputum more desirable than induced specimens
bull Collect sputum before treatment is initiated
11
Interpretation of sputum stained by
Z N Stain (WHO )
More than 10 bacilli field ------- +++
From 1 ndash 10 bacilli field ------- ++
From 10 ndash 99 bacilli 100 fields ----- +
From 1 -9 bacilli100 fields ------ write the no
No bacilli seen ---------- negative
2- Detecting AFB by fluorochrome stain using fluorescence microscopy
The smear may be stained by auramine-O dye In this method the TB bacilli are stained yellow against dark background amp easily visualized using florescent microscope
Advantages
- More sensitive
- Rapid
Disadvantages
- Hazards of dye toxicity
- more expensive
- must be confirmed by Z-N stain
Acid Fast Bacilli under Fluorescent Microscope
DrTVRao MD 14
Culturebull Used to confirm
diagnosis of TB
bull Culture all
specimens even if
smear is negative
bull Initial drug isolate
should be used to
determine drug
susceptibility15
Laboratory Diagnosis
1- Sputum smears stained by Z-N stain
Three morning successive mucopurulent sputum samples are needed to diagnose pulmonary TB
Advantage - cheap ndash rapid
- Easy to perform
- High predictive value gt 90
- Specificity of 98
Disadvantages
- sputum ( need to contain 5000-10000 AFB ml)
- Young children elderly amp HIV infected persons may not produce cavities amp sputum containing AFB
DrTVRao MD 16
2- Detecting AFB by fluorochrome stain using fluorescence microscopy
The smear may be stained by aura mine-O dye In this method the TB bacilli are stained yellow against dark background amp easily visualized using florescent microscope
Advantages
- More sensitive
- Rapid
Disadvantages
- Hazards of dye toxicity
- more expensive
- must be confirmed by Z-N stain
DrTVRao MD 17
LowensteinndashJensen mediumbull When grown on LJ
medium M tuberculosis appears as brown granular colonies (sometimes called buff rough and tough) The media must be incubated for a significant length of time usually four weeks due to the slow doubling time of M tuberculosis DrTVRao MD 18
3- Cultures on L J media
Lowenstein ndashJensen medium is an egg based media
with addition of salts 5 glycerol Malachite green
Advantages - Specificity about 99
- More sensitive (need lower no of bacilli 10-100 ml)
- Can differentiate between TB complex amp NTM using biochemical reactions
- Sensitivity tests for antituberculous drugs
( St INH Rif E)
Disadvantages Slowly growing ( up to 8 weeks )DrTVRao MD 19
Recent Methods for Diagnosis
I ndashBACTEC 460 ( rapid radiometric culture system )specimens are cultured in a liquid medium
(Middle brook7H9 broth base )containing C14 ndashlabelled palmitic acid amp PANTA antibiotic mixture
Growing mycobacteria utilize the acid releasing radioactive CO2 which is measured as growth index (GI) in the BACTEC instrument
The daily increase in GI output is directly proportional to the rate amp amount of growth in the medium
Mycobacteria Growth Indicator
Tube (MGIT)
Tube contains modified Middlebrook 7H9
broth base with OADC enrichment amp
PANTA antibiotic mixture
All types of clinical specimens pulmonary
as well as extra-pulmonary ( except
blood) could be cultured on this type of
media
The MGIT 960 System
The MGIT 960 system is a non-radiometeric
automated system that uses the MGIT media amp
sensors to detect the fluorescence
Advantages
-The system holds 960 plastic tubes which are
continuously monitored
- Early detection as the machine monitoring amp
reading the tubes every hour
Detection and identification of mycobacteria directly
from clinical samplesbull Genotypic Methods
bull 1048708 PCR
bull 1048708 LAMP
bull 1048708 TMA NAA
bull 1048708 Ligase chain reaction
bull 1048708 Phenotypic Methods
bull 1048708 FAST Plaque TB
DrTVRao MD 23
bull Essentially PCR is a way to make millions of identical copies of a specific DNA sequence which may be a gene or a part of a gene or simply a stretch of nucleotides with a known DNA sequence the function of which may be unknown
Polymerase Chain Reaction (PCR)
DrTVRao MD 24
Polymerase Chain Reaction (PCR) amp
Gene probeNucleic acid probes amp nucleic acid amplification
tests in which polymerase enzymes are used to
amplify ( make many copies of specific DNA or
RNA sequences extracted from mycobacterial
cells
Advantages
- Rapid procedure - High sensitivity (1-10
( 3 ndash 4 hours) bacilli ml sputum)
bull Interferon-γ assays measure cell-mediated immunity by quantifying IFN-γ released from sensitized T cells in whole bloodPBMCs incubated with TB antigens
Quantiferon-GOLD
DrTVRao MD 26
What Positive Skin Test ( Tuberculin Test means)
bull A positive TB skin test or TB blood test only tells that a person has been infected with TB bacteria It does not tell whether the person has latent TB infection (LTBI) or has progressed to TB disease
DrTVRao MD 27
Tuberculin TestInterpretation A positive test indicates previous exposure and
carriage of TB A negative tuberculin test excludes infection in
suspected persons Tuberculin positive persons may develop
reactivation type of TB Tuberculin negative persons are at risk of gaining
new infection False positive reactions are mainly due to
- Infection with nontuberculous mycobacteria
DrTVRao MD 28
False negative reactions may be due to-
bull False negative reactions may be due to
- Sever tuberculosis infection (Miliary TB) -Hodgkinrsquos disease
bull Corticosteroid therapy - Malnutrition -AIDS
bull Children below 5 years of age with no exposure history
bull Positive test must be regarded suspicious
DrTVRao MD 29
Tuberculin Test( Mantoux Test )
bull Test to be interpreted in relation to clinical evaluation
bull Even the induration of 5 mm to be considered positive when tested on HIV patients
bull Lacks specificity
Positive Test Means
bull This means the personrsquos body was infected with TB bacteria Additional tests are needed to determine if the person has latent TB infection or TB disease A health care worker will then provide treatment as needed
DrTVRao MD 31
Negative Test Means
bull This means the personrsquos body did not react to the test and that latent TB infection or TB disease is not likely
DrTVRao MD 32
Tuberculin Testing - Limitations
bull False positive reactions are mainly due to
bull - Infection with nontuberculous mycobacteria
bull False negative reactions may be due to
bull - Sever tuberculosis infection (Miliary TB) -Hodgkinrsquos disease
bull - Corticosteroid therapy - Malnutrition -AIDS
bull Children below 5 years of age with no exposure history
bull - Positive test must be regarded suspicious DrTVRao MD 33
Recent Methods for Diagnosis
I ndash BACTEC 460 ( rapid radiometric culture system )
Specimens are cultured in a liquid medium (Middle brook7H9 broth base )containing C14 ndash labeled palmitic acid amp PANTA antibiotic mixture
Growing mycobacteria utilize the acid releasing radioactive CO2 which is measured as growth index (GI) in the BACTEC instrument
The daily increase in GI output is directly proportional to the rate amp amount of growth in the medium
DrTVRao MD 34
TB blood testsbull TB blood tests (also called interferon-gamma
release assays or IGRAs) measure how the immune system reacts to the bacteria that cause TB An IGRA measures how strong a personrsquos immune system reacts to TB bacteria by testing the personrsquos blood in a laboratory
bull Two IGRAs are approved by the US Food and Drug Administration (FDA) and are available in the United States
DrTVRao MD 35
Positive IGRAbull This means that the
person has been infected with TB bacteria Additional tests are needed to determine if the person has latent TB infection or TB disease A health care worker will then provide treatment as needed
DrTVRao MD 36
Negative IGRA
bull This means that the personrsquos blood did not react to the test and that latent TB infection or TB disease is not likely
DrTVRao MD 37
IGRAs are the preferred method of TB infection testing for the following
People who have received bacilli ChalmettendashGueacuterin (BCG) BCG is a vaccine for TB disease People who have a difficult time returning for a second appointment to look for a reaction to the TST
There is no problem with repeated IGRAs
DrTVRao MD 38
III Polymerase Chain Reaction
(PCR) amp Gene probeNucleic acid probes amp nucleic acid amplification
tests in which polymerase enzymes are used to
amplify ( make many copies of specific DNA or
RNA sequences extracted from mycobacterial
cells
Advantages
- Rapid procedure - High sensitivity (1-10
( 3 ndash 4 hours) bacilli ml sputum)
DrTVRao MD 39
Molecular DR testing is particularly useful for
bull Patients suspected or at high risk of having drug-resistant TBvery ill patients for whom drug-susceptibility information might alter case management decisions such as patients who do not get better while taking standard first-line therapy
DrTVRao MD 40
Detection of MDR Tuberculosis
bull Very ill patients for whom drug-susceptibility information might alter case management decisions such as patients who do not get better while taking standard first-line therapy
DrTVRao MD 41
Detection of MDR Tuberculosis
bull outbreak or contact investigations when drug resistance is suspected in the source case or in some severely immunocompromised persons such as HIV-infected persons or those receiving dialysis in which knowledge of drug-susceptibility would be a significant benefit and affect preventive therapy decisions
DrTVRao MD 42
Tuberculosis and HIV infection
bull HIV association has become a threat to the developed countries too
bull HIV association will lead to rapid spread of tuberculosis
DrTVRao MD 43
HIV Considerations
bull HIV is the strongest risk factor for progression to active disease
bull HIV kills CD4+ T Helper cells which normally inhibit M tuberculosis
bull HIV interferes with PPD skin test
bull Protease inhibitors interfere with rifampin
DrTVRao MD 44
Epidemiologybull An ancient disease called as white plague
bull 13 of the world population is infected
bull 2 billion infected
bull Each year 9 lakhs to 1 million are infected
bull Poor nations phase the burnt of the disease
bull In developing world gt 4o of the population is effected
bull 15 million suffer the disease
bull 3 million are highly infective
DrTVRao MD 45
MDR tuberculosis
bull Multidrug resistant tuberculosis has become a global threat
bull In 1993 WHO declared Tuberculosis a Global emergency
bull Animals shed the bacilli in Milk humanrsquos get infected after drinking the unsterilized Milk
bull Pasteurization has reduced the incidence of Bovine tuberculosis
DrTVRao MD 46
Why Tuberculosis continues to be Important
bull Someone in the world is newly infected with TB bacilli every second
bull Overall one-third of the worlds population is currently infected with the TB bacillus
bull 5-10 of people who are infected with TB bacilli (but who are not infected with HIV) become sick or infectious at some time during their life People with HIV and TB infection are much more likely to develop TB
DrTVRao MD 47
bull Programme Created by DrTVRao MD for Medical and Paramedical
Students in Developing world
bull Email
bull doctortvraogmailcom
DrTVRao MD 48
![Page 3: Diagnosis of tuberculosis an Update](https://reader031.fdocuments.in/reader031/viewer/2022032113/55a62b711a28abd5138b48bb/html5/thumbnails/3.jpg)
Diagnosis of TB Disease
bull People suspected of having TB disease should be referred for a medical evaluation which will include
Medical history Physical examination
Test for TB infection (TB skin test or TB blood test)
bull Chest radiograph (X-ray) and
bull Appropriate laboratory tests
DrTVRao MD 3
Who Should Get Tested for TB
bull TB tests are generally not needed for people with a low risk of infection with TB bacteria
bull Certain people should be tested for TB bacteria because they are more likely to get TB disease including
bull People who have spent time with someone who has TB disease People with HIV infection or another medical problem that weakens the immune system
bull People who have symptoms of TB disease (fever night sweats cough and weight loss)
DrTVRao MD 4
Who Should Get Tested for TB
bull People who have spent time with someone who has TB disease
bull People with HIV infection or another medical problem that weakens the immune system
bull People who have symptoms of TB disease (fever night sweats cough and weight loss)
DrTVRao MD 5
Who Should Get Tested for TB
bull People from a country where TB disease is common (most countries in Latin America the Caribbean Africa Asia Eastern Europe and Russia)
bull People who live or work somewhere in the United States where TB disease is more common (homeless shelters prison or jails or some nursing homes)
bull People who use illegal drugsDrTVRao MD 6
X ray of Chest a Commonly used Diagnostic tool
bull Acute pulmonary TB can be easily seen on an X-ray However the picture it presents is not specific and a normal chest X-ray cannot exclude extrapulmonary TB Also in countries where resources are more limited there is often a lack of X-ray facilitiesDrTVRao MD 7
Other testsbull Other tests such
as a chest x-ray and a sample of sputum are needed to see whether the person has TB disease
DrTVRao MD 8
Types of specimens-Sputum
- BAL
-Pleural effusions
- Urine
- Stool
-CSF
-Aspiration ( gastric ndash cold abscess)
- Blood in case of haematogenous TB
DrTVRao MD 9
Laboratory Diagnosis
1- Sputum smears stained by Z-N stain
Three morning successive mucopurulent sputum samples are needed to diagnose pulmonary TB
Advantage - cheap ndash rapid
- Easy to perform
- High predictive value gt 90
- Specificity of 98
Disadvantages
- sputum ( need to contain 5000-10000 AFB ml)
- Young children elderly amp HIV infected persons may not produce cavities amp sputum containing AFB
Sputum Collectionbull Sputum specimens
are essential to confirm TBndash Specimens should be
from lung secretions not saliva
bull Collect 3 specimens on 3 different days
bull Spontaneous morning sputum more desirable than induced specimens
bull Collect sputum before treatment is initiated
11
Interpretation of sputum stained by
Z N Stain (WHO )
More than 10 bacilli field ------- +++
From 1 ndash 10 bacilli field ------- ++
From 10 ndash 99 bacilli 100 fields ----- +
From 1 -9 bacilli100 fields ------ write the no
No bacilli seen ---------- negative
2- Detecting AFB by fluorochrome stain using fluorescence microscopy
The smear may be stained by auramine-O dye In this method the TB bacilli are stained yellow against dark background amp easily visualized using florescent microscope
Advantages
- More sensitive
- Rapid
Disadvantages
- Hazards of dye toxicity
- more expensive
- must be confirmed by Z-N stain
Acid Fast Bacilli under Fluorescent Microscope
DrTVRao MD 14
Culturebull Used to confirm
diagnosis of TB
bull Culture all
specimens even if
smear is negative
bull Initial drug isolate
should be used to
determine drug
susceptibility15
Laboratory Diagnosis
1- Sputum smears stained by Z-N stain
Three morning successive mucopurulent sputum samples are needed to diagnose pulmonary TB
Advantage - cheap ndash rapid
- Easy to perform
- High predictive value gt 90
- Specificity of 98
Disadvantages
- sputum ( need to contain 5000-10000 AFB ml)
- Young children elderly amp HIV infected persons may not produce cavities amp sputum containing AFB
DrTVRao MD 16
2- Detecting AFB by fluorochrome stain using fluorescence microscopy
The smear may be stained by aura mine-O dye In this method the TB bacilli are stained yellow against dark background amp easily visualized using florescent microscope
Advantages
- More sensitive
- Rapid
Disadvantages
- Hazards of dye toxicity
- more expensive
- must be confirmed by Z-N stain
DrTVRao MD 17
LowensteinndashJensen mediumbull When grown on LJ
medium M tuberculosis appears as brown granular colonies (sometimes called buff rough and tough) The media must be incubated for a significant length of time usually four weeks due to the slow doubling time of M tuberculosis DrTVRao MD 18
3- Cultures on L J media
Lowenstein ndashJensen medium is an egg based media
with addition of salts 5 glycerol Malachite green
Advantages - Specificity about 99
- More sensitive (need lower no of bacilli 10-100 ml)
- Can differentiate between TB complex amp NTM using biochemical reactions
- Sensitivity tests for antituberculous drugs
( St INH Rif E)
Disadvantages Slowly growing ( up to 8 weeks )DrTVRao MD 19
Recent Methods for Diagnosis
I ndashBACTEC 460 ( rapid radiometric culture system )specimens are cultured in a liquid medium
(Middle brook7H9 broth base )containing C14 ndashlabelled palmitic acid amp PANTA antibiotic mixture
Growing mycobacteria utilize the acid releasing radioactive CO2 which is measured as growth index (GI) in the BACTEC instrument
The daily increase in GI output is directly proportional to the rate amp amount of growth in the medium
Mycobacteria Growth Indicator
Tube (MGIT)
Tube contains modified Middlebrook 7H9
broth base with OADC enrichment amp
PANTA antibiotic mixture
All types of clinical specimens pulmonary
as well as extra-pulmonary ( except
blood) could be cultured on this type of
media
The MGIT 960 System
The MGIT 960 system is a non-radiometeric
automated system that uses the MGIT media amp
sensors to detect the fluorescence
Advantages
-The system holds 960 plastic tubes which are
continuously monitored
- Early detection as the machine monitoring amp
reading the tubes every hour
Detection and identification of mycobacteria directly
from clinical samplesbull Genotypic Methods
bull 1048708 PCR
bull 1048708 LAMP
bull 1048708 TMA NAA
bull 1048708 Ligase chain reaction
bull 1048708 Phenotypic Methods
bull 1048708 FAST Plaque TB
DrTVRao MD 23
bull Essentially PCR is a way to make millions of identical copies of a specific DNA sequence which may be a gene or a part of a gene or simply a stretch of nucleotides with a known DNA sequence the function of which may be unknown
Polymerase Chain Reaction (PCR)
DrTVRao MD 24
Polymerase Chain Reaction (PCR) amp
Gene probeNucleic acid probes amp nucleic acid amplification
tests in which polymerase enzymes are used to
amplify ( make many copies of specific DNA or
RNA sequences extracted from mycobacterial
cells
Advantages
- Rapid procedure - High sensitivity (1-10
( 3 ndash 4 hours) bacilli ml sputum)
bull Interferon-γ assays measure cell-mediated immunity by quantifying IFN-γ released from sensitized T cells in whole bloodPBMCs incubated with TB antigens
Quantiferon-GOLD
DrTVRao MD 26
What Positive Skin Test ( Tuberculin Test means)
bull A positive TB skin test or TB blood test only tells that a person has been infected with TB bacteria It does not tell whether the person has latent TB infection (LTBI) or has progressed to TB disease
DrTVRao MD 27
Tuberculin TestInterpretation A positive test indicates previous exposure and
carriage of TB A negative tuberculin test excludes infection in
suspected persons Tuberculin positive persons may develop
reactivation type of TB Tuberculin negative persons are at risk of gaining
new infection False positive reactions are mainly due to
- Infection with nontuberculous mycobacteria
DrTVRao MD 28
False negative reactions may be due to-
bull False negative reactions may be due to
- Sever tuberculosis infection (Miliary TB) -Hodgkinrsquos disease
bull Corticosteroid therapy - Malnutrition -AIDS
bull Children below 5 years of age with no exposure history
bull Positive test must be regarded suspicious
DrTVRao MD 29
Tuberculin Test( Mantoux Test )
bull Test to be interpreted in relation to clinical evaluation
bull Even the induration of 5 mm to be considered positive when tested on HIV patients
bull Lacks specificity
Positive Test Means
bull This means the personrsquos body was infected with TB bacteria Additional tests are needed to determine if the person has latent TB infection or TB disease A health care worker will then provide treatment as needed
DrTVRao MD 31
Negative Test Means
bull This means the personrsquos body did not react to the test and that latent TB infection or TB disease is not likely
DrTVRao MD 32
Tuberculin Testing - Limitations
bull False positive reactions are mainly due to
bull - Infection with nontuberculous mycobacteria
bull False negative reactions may be due to
bull - Sever tuberculosis infection (Miliary TB) -Hodgkinrsquos disease
bull - Corticosteroid therapy - Malnutrition -AIDS
bull Children below 5 years of age with no exposure history
bull - Positive test must be regarded suspicious DrTVRao MD 33
Recent Methods for Diagnosis
I ndash BACTEC 460 ( rapid radiometric culture system )
Specimens are cultured in a liquid medium (Middle brook7H9 broth base )containing C14 ndash labeled palmitic acid amp PANTA antibiotic mixture
Growing mycobacteria utilize the acid releasing radioactive CO2 which is measured as growth index (GI) in the BACTEC instrument
The daily increase in GI output is directly proportional to the rate amp amount of growth in the medium
DrTVRao MD 34
TB blood testsbull TB blood tests (also called interferon-gamma
release assays or IGRAs) measure how the immune system reacts to the bacteria that cause TB An IGRA measures how strong a personrsquos immune system reacts to TB bacteria by testing the personrsquos blood in a laboratory
bull Two IGRAs are approved by the US Food and Drug Administration (FDA) and are available in the United States
DrTVRao MD 35
Positive IGRAbull This means that the
person has been infected with TB bacteria Additional tests are needed to determine if the person has latent TB infection or TB disease A health care worker will then provide treatment as needed
DrTVRao MD 36
Negative IGRA
bull This means that the personrsquos blood did not react to the test and that latent TB infection or TB disease is not likely
DrTVRao MD 37
IGRAs are the preferred method of TB infection testing for the following
People who have received bacilli ChalmettendashGueacuterin (BCG) BCG is a vaccine for TB disease People who have a difficult time returning for a second appointment to look for a reaction to the TST
There is no problem with repeated IGRAs
DrTVRao MD 38
III Polymerase Chain Reaction
(PCR) amp Gene probeNucleic acid probes amp nucleic acid amplification
tests in which polymerase enzymes are used to
amplify ( make many copies of specific DNA or
RNA sequences extracted from mycobacterial
cells
Advantages
- Rapid procedure - High sensitivity (1-10
( 3 ndash 4 hours) bacilli ml sputum)
DrTVRao MD 39
Molecular DR testing is particularly useful for
bull Patients suspected or at high risk of having drug-resistant TBvery ill patients for whom drug-susceptibility information might alter case management decisions such as patients who do not get better while taking standard first-line therapy
DrTVRao MD 40
Detection of MDR Tuberculosis
bull Very ill patients for whom drug-susceptibility information might alter case management decisions such as patients who do not get better while taking standard first-line therapy
DrTVRao MD 41
Detection of MDR Tuberculosis
bull outbreak or contact investigations when drug resistance is suspected in the source case or in some severely immunocompromised persons such as HIV-infected persons or those receiving dialysis in which knowledge of drug-susceptibility would be a significant benefit and affect preventive therapy decisions
DrTVRao MD 42
Tuberculosis and HIV infection
bull HIV association has become a threat to the developed countries too
bull HIV association will lead to rapid spread of tuberculosis
DrTVRao MD 43
HIV Considerations
bull HIV is the strongest risk factor for progression to active disease
bull HIV kills CD4+ T Helper cells which normally inhibit M tuberculosis
bull HIV interferes with PPD skin test
bull Protease inhibitors interfere with rifampin
DrTVRao MD 44
Epidemiologybull An ancient disease called as white plague
bull 13 of the world population is infected
bull 2 billion infected
bull Each year 9 lakhs to 1 million are infected
bull Poor nations phase the burnt of the disease
bull In developing world gt 4o of the population is effected
bull 15 million suffer the disease
bull 3 million are highly infective
DrTVRao MD 45
MDR tuberculosis
bull Multidrug resistant tuberculosis has become a global threat
bull In 1993 WHO declared Tuberculosis a Global emergency
bull Animals shed the bacilli in Milk humanrsquos get infected after drinking the unsterilized Milk
bull Pasteurization has reduced the incidence of Bovine tuberculosis
DrTVRao MD 46
Why Tuberculosis continues to be Important
bull Someone in the world is newly infected with TB bacilli every second
bull Overall one-third of the worlds population is currently infected with the TB bacillus
bull 5-10 of people who are infected with TB bacilli (but who are not infected with HIV) become sick or infectious at some time during their life People with HIV and TB infection are much more likely to develop TB
DrTVRao MD 47
bull Programme Created by DrTVRao MD for Medical and Paramedical
Students in Developing world
bull Email
bull doctortvraogmailcom
DrTVRao MD 48
![Page 4: Diagnosis of tuberculosis an Update](https://reader031.fdocuments.in/reader031/viewer/2022032113/55a62b711a28abd5138b48bb/html5/thumbnails/4.jpg)
Who Should Get Tested for TB
bull TB tests are generally not needed for people with a low risk of infection with TB bacteria
bull Certain people should be tested for TB bacteria because they are more likely to get TB disease including
bull People who have spent time with someone who has TB disease People with HIV infection or another medical problem that weakens the immune system
bull People who have symptoms of TB disease (fever night sweats cough and weight loss)
DrTVRao MD 4
Who Should Get Tested for TB
bull People who have spent time with someone who has TB disease
bull People with HIV infection or another medical problem that weakens the immune system
bull People who have symptoms of TB disease (fever night sweats cough and weight loss)
DrTVRao MD 5
Who Should Get Tested for TB
bull People from a country where TB disease is common (most countries in Latin America the Caribbean Africa Asia Eastern Europe and Russia)
bull People who live or work somewhere in the United States where TB disease is more common (homeless shelters prison or jails or some nursing homes)
bull People who use illegal drugsDrTVRao MD 6
X ray of Chest a Commonly used Diagnostic tool
bull Acute pulmonary TB can be easily seen on an X-ray However the picture it presents is not specific and a normal chest X-ray cannot exclude extrapulmonary TB Also in countries where resources are more limited there is often a lack of X-ray facilitiesDrTVRao MD 7
Other testsbull Other tests such
as a chest x-ray and a sample of sputum are needed to see whether the person has TB disease
DrTVRao MD 8
Types of specimens-Sputum
- BAL
-Pleural effusions
- Urine
- Stool
-CSF
-Aspiration ( gastric ndash cold abscess)
- Blood in case of haematogenous TB
DrTVRao MD 9
Laboratory Diagnosis
1- Sputum smears stained by Z-N stain
Three morning successive mucopurulent sputum samples are needed to diagnose pulmonary TB
Advantage - cheap ndash rapid
- Easy to perform
- High predictive value gt 90
- Specificity of 98
Disadvantages
- sputum ( need to contain 5000-10000 AFB ml)
- Young children elderly amp HIV infected persons may not produce cavities amp sputum containing AFB
Sputum Collectionbull Sputum specimens
are essential to confirm TBndash Specimens should be
from lung secretions not saliva
bull Collect 3 specimens on 3 different days
bull Spontaneous morning sputum more desirable than induced specimens
bull Collect sputum before treatment is initiated
11
Interpretation of sputum stained by
Z N Stain (WHO )
More than 10 bacilli field ------- +++
From 1 ndash 10 bacilli field ------- ++
From 10 ndash 99 bacilli 100 fields ----- +
From 1 -9 bacilli100 fields ------ write the no
No bacilli seen ---------- negative
2- Detecting AFB by fluorochrome stain using fluorescence microscopy
The smear may be stained by auramine-O dye In this method the TB bacilli are stained yellow against dark background amp easily visualized using florescent microscope
Advantages
- More sensitive
- Rapid
Disadvantages
- Hazards of dye toxicity
- more expensive
- must be confirmed by Z-N stain
Acid Fast Bacilli under Fluorescent Microscope
DrTVRao MD 14
Culturebull Used to confirm
diagnosis of TB
bull Culture all
specimens even if
smear is negative
bull Initial drug isolate
should be used to
determine drug
susceptibility15
Laboratory Diagnosis
1- Sputum smears stained by Z-N stain
Three morning successive mucopurulent sputum samples are needed to diagnose pulmonary TB
Advantage - cheap ndash rapid
- Easy to perform
- High predictive value gt 90
- Specificity of 98
Disadvantages
- sputum ( need to contain 5000-10000 AFB ml)
- Young children elderly amp HIV infected persons may not produce cavities amp sputum containing AFB
DrTVRao MD 16
2- Detecting AFB by fluorochrome stain using fluorescence microscopy
The smear may be stained by aura mine-O dye In this method the TB bacilli are stained yellow against dark background amp easily visualized using florescent microscope
Advantages
- More sensitive
- Rapid
Disadvantages
- Hazards of dye toxicity
- more expensive
- must be confirmed by Z-N stain
DrTVRao MD 17
LowensteinndashJensen mediumbull When grown on LJ
medium M tuberculosis appears as brown granular colonies (sometimes called buff rough and tough) The media must be incubated for a significant length of time usually four weeks due to the slow doubling time of M tuberculosis DrTVRao MD 18
3- Cultures on L J media
Lowenstein ndashJensen medium is an egg based media
with addition of salts 5 glycerol Malachite green
Advantages - Specificity about 99
- More sensitive (need lower no of bacilli 10-100 ml)
- Can differentiate between TB complex amp NTM using biochemical reactions
- Sensitivity tests for antituberculous drugs
( St INH Rif E)
Disadvantages Slowly growing ( up to 8 weeks )DrTVRao MD 19
Recent Methods for Diagnosis
I ndashBACTEC 460 ( rapid radiometric culture system )specimens are cultured in a liquid medium
(Middle brook7H9 broth base )containing C14 ndashlabelled palmitic acid amp PANTA antibiotic mixture
Growing mycobacteria utilize the acid releasing radioactive CO2 which is measured as growth index (GI) in the BACTEC instrument
The daily increase in GI output is directly proportional to the rate amp amount of growth in the medium
Mycobacteria Growth Indicator
Tube (MGIT)
Tube contains modified Middlebrook 7H9
broth base with OADC enrichment amp
PANTA antibiotic mixture
All types of clinical specimens pulmonary
as well as extra-pulmonary ( except
blood) could be cultured on this type of
media
The MGIT 960 System
The MGIT 960 system is a non-radiometeric
automated system that uses the MGIT media amp
sensors to detect the fluorescence
Advantages
-The system holds 960 plastic tubes which are
continuously monitored
- Early detection as the machine monitoring amp
reading the tubes every hour
Detection and identification of mycobacteria directly
from clinical samplesbull Genotypic Methods
bull 1048708 PCR
bull 1048708 LAMP
bull 1048708 TMA NAA
bull 1048708 Ligase chain reaction
bull 1048708 Phenotypic Methods
bull 1048708 FAST Plaque TB
DrTVRao MD 23
bull Essentially PCR is a way to make millions of identical copies of a specific DNA sequence which may be a gene or a part of a gene or simply a stretch of nucleotides with a known DNA sequence the function of which may be unknown
Polymerase Chain Reaction (PCR)
DrTVRao MD 24
Polymerase Chain Reaction (PCR) amp
Gene probeNucleic acid probes amp nucleic acid amplification
tests in which polymerase enzymes are used to
amplify ( make many copies of specific DNA or
RNA sequences extracted from mycobacterial
cells
Advantages
- Rapid procedure - High sensitivity (1-10
( 3 ndash 4 hours) bacilli ml sputum)
bull Interferon-γ assays measure cell-mediated immunity by quantifying IFN-γ released from sensitized T cells in whole bloodPBMCs incubated with TB antigens
Quantiferon-GOLD
DrTVRao MD 26
What Positive Skin Test ( Tuberculin Test means)
bull A positive TB skin test or TB blood test only tells that a person has been infected with TB bacteria It does not tell whether the person has latent TB infection (LTBI) or has progressed to TB disease
DrTVRao MD 27
Tuberculin TestInterpretation A positive test indicates previous exposure and
carriage of TB A negative tuberculin test excludes infection in
suspected persons Tuberculin positive persons may develop
reactivation type of TB Tuberculin negative persons are at risk of gaining
new infection False positive reactions are mainly due to
- Infection with nontuberculous mycobacteria
DrTVRao MD 28
False negative reactions may be due to-
bull False negative reactions may be due to
- Sever tuberculosis infection (Miliary TB) -Hodgkinrsquos disease
bull Corticosteroid therapy - Malnutrition -AIDS
bull Children below 5 years of age with no exposure history
bull Positive test must be regarded suspicious
DrTVRao MD 29
Tuberculin Test( Mantoux Test )
bull Test to be interpreted in relation to clinical evaluation
bull Even the induration of 5 mm to be considered positive when tested on HIV patients
bull Lacks specificity
Positive Test Means
bull This means the personrsquos body was infected with TB bacteria Additional tests are needed to determine if the person has latent TB infection or TB disease A health care worker will then provide treatment as needed
DrTVRao MD 31
Negative Test Means
bull This means the personrsquos body did not react to the test and that latent TB infection or TB disease is not likely
DrTVRao MD 32
Tuberculin Testing - Limitations
bull False positive reactions are mainly due to
bull - Infection with nontuberculous mycobacteria
bull False negative reactions may be due to
bull - Sever tuberculosis infection (Miliary TB) -Hodgkinrsquos disease
bull - Corticosteroid therapy - Malnutrition -AIDS
bull Children below 5 years of age with no exposure history
bull - Positive test must be regarded suspicious DrTVRao MD 33
Recent Methods for Diagnosis
I ndash BACTEC 460 ( rapid radiometric culture system )
Specimens are cultured in a liquid medium (Middle brook7H9 broth base )containing C14 ndash labeled palmitic acid amp PANTA antibiotic mixture
Growing mycobacteria utilize the acid releasing radioactive CO2 which is measured as growth index (GI) in the BACTEC instrument
The daily increase in GI output is directly proportional to the rate amp amount of growth in the medium
DrTVRao MD 34
TB blood testsbull TB blood tests (also called interferon-gamma
release assays or IGRAs) measure how the immune system reacts to the bacteria that cause TB An IGRA measures how strong a personrsquos immune system reacts to TB bacteria by testing the personrsquos blood in a laboratory
bull Two IGRAs are approved by the US Food and Drug Administration (FDA) and are available in the United States
DrTVRao MD 35
Positive IGRAbull This means that the
person has been infected with TB bacteria Additional tests are needed to determine if the person has latent TB infection or TB disease A health care worker will then provide treatment as needed
DrTVRao MD 36
Negative IGRA
bull This means that the personrsquos blood did not react to the test and that latent TB infection or TB disease is not likely
DrTVRao MD 37
IGRAs are the preferred method of TB infection testing for the following
People who have received bacilli ChalmettendashGueacuterin (BCG) BCG is a vaccine for TB disease People who have a difficult time returning for a second appointment to look for a reaction to the TST
There is no problem with repeated IGRAs
DrTVRao MD 38
III Polymerase Chain Reaction
(PCR) amp Gene probeNucleic acid probes amp nucleic acid amplification
tests in which polymerase enzymes are used to
amplify ( make many copies of specific DNA or
RNA sequences extracted from mycobacterial
cells
Advantages
- Rapid procedure - High sensitivity (1-10
( 3 ndash 4 hours) bacilli ml sputum)
DrTVRao MD 39
Molecular DR testing is particularly useful for
bull Patients suspected or at high risk of having drug-resistant TBvery ill patients for whom drug-susceptibility information might alter case management decisions such as patients who do not get better while taking standard first-line therapy
DrTVRao MD 40
Detection of MDR Tuberculosis
bull Very ill patients for whom drug-susceptibility information might alter case management decisions such as patients who do not get better while taking standard first-line therapy
DrTVRao MD 41
Detection of MDR Tuberculosis
bull outbreak or contact investigations when drug resistance is suspected in the source case or in some severely immunocompromised persons such as HIV-infected persons or those receiving dialysis in which knowledge of drug-susceptibility would be a significant benefit and affect preventive therapy decisions
DrTVRao MD 42
Tuberculosis and HIV infection
bull HIV association has become a threat to the developed countries too
bull HIV association will lead to rapid spread of tuberculosis
DrTVRao MD 43
HIV Considerations
bull HIV is the strongest risk factor for progression to active disease
bull HIV kills CD4+ T Helper cells which normally inhibit M tuberculosis
bull HIV interferes with PPD skin test
bull Protease inhibitors interfere with rifampin
DrTVRao MD 44
Epidemiologybull An ancient disease called as white plague
bull 13 of the world population is infected
bull 2 billion infected
bull Each year 9 lakhs to 1 million are infected
bull Poor nations phase the burnt of the disease
bull In developing world gt 4o of the population is effected
bull 15 million suffer the disease
bull 3 million are highly infective
DrTVRao MD 45
MDR tuberculosis
bull Multidrug resistant tuberculosis has become a global threat
bull In 1993 WHO declared Tuberculosis a Global emergency
bull Animals shed the bacilli in Milk humanrsquos get infected after drinking the unsterilized Milk
bull Pasteurization has reduced the incidence of Bovine tuberculosis
DrTVRao MD 46
Why Tuberculosis continues to be Important
bull Someone in the world is newly infected with TB bacilli every second
bull Overall one-third of the worlds population is currently infected with the TB bacillus
bull 5-10 of people who are infected with TB bacilli (but who are not infected with HIV) become sick or infectious at some time during their life People with HIV and TB infection are much more likely to develop TB
DrTVRao MD 47
bull Programme Created by DrTVRao MD for Medical and Paramedical
Students in Developing world
bull Email
bull doctortvraogmailcom
DrTVRao MD 48
![Page 5: Diagnosis of tuberculosis an Update](https://reader031.fdocuments.in/reader031/viewer/2022032113/55a62b711a28abd5138b48bb/html5/thumbnails/5.jpg)
Who Should Get Tested for TB
bull People who have spent time with someone who has TB disease
bull People with HIV infection or another medical problem that weakens the immune system
bull People who have symptoms of TB disease (fever night sweats cough and weight loss)
DrTVRao MD 5
Who Should Get Tested for TB
bull People from a country where TB disease is common (most countries in Latin America the Caribbean Africa Asia Eastern Europe and Russia)
bull People who live or work somewhere in the United States where TB disease is more common (homeless shelters prison or jails or some nursing homes)
bull People who use illegal drugsDrTVRao MD 6
X ray of Chest a Commonly used Diagnostic tool
bull Acute pulmonary TB can be easily seen on an X-ray However the picture it presents is not specific and a normal chest X-ray cannot exclude extrapulmonary TB Also in countries where resources are more limited there is often a lack of X-ray facilitiesDrTVRao MD 7
Other testsbull Other tests such
as a chest x-ray and a sample of sputum are needed to see whether the person has TB disease
DrTVRao MD 8
Types of specimens-Sputum
- BAL
-Pleural effusions
- Urine
- Stool
-CSF
-Aspiration ( gastric ndash cold abscess)
- Blood in case of haematogenous TB
DrTVRao MD 9
Laboratory Diagnosis
1- Sputum smears stained by Z-N stain
Three morning successive mucopurulent sputum samples are needed to diagnose pulmonary TB
Advantage - cheap ndash rapid
- Easy to perform
- High predictive value gt 90
- Specificity of 98
Disadvantages
- sputum ( need to contain 5000-10000 AFB ml)
- Young children elderly amp HIV infected persons may not produce cavities amp sputum containing AFB
Sputum Collectionbull Sputum specimens
are essential to confirm TBndash Specimens should be
from lung secretions not saliva
bull Collect 3 specimens on 3 different days
bull Spontaneous morning sputum more desirable than induced specimens
bull Collect sputum before treatment is initiated
11
Interpretation of sputum stained by
Z N Stain (WHO )
More than 10 bacilli field ------- +++
From 1 ndash 10 bacilli field ------- ++
From 10 ndash 99 bacilli 100 fields ----- +
From 1 -9 bacilli100 fields ------ write the no
No bacilli seen ---------- negative
2- Detecting AFB by fluorochrome stain using fluorescence microscopy
The smear may be stained by auramine-O dye In this method the TB bacilli are stained yellow against dark background amp easily visualized using florescent microscope
Advantages
- More sensitive
- Rapid
Disadvantages
- Hazards of dye toxicity
- more expensive
- must be confirmed by Z-N stain
Acid Fast Bacilli under Fluorescent Microscope
DrTVRao MD 14
Culturebull Used to confirm
diagnosis of TB
bull Culture all
specimens even if
smear is negative
bull Initial drug isolate
should be used to
determine drug
susceptibility15
Laboratory Diagnosis
1- Sputum smears stained by Z-N stain
Three morning successive mucopurulent sputum samples are needed to diagnose pulmonary TB
Advantage - cheap ndash rapid
- Easy to perform
- High predictive value gt 90
- Specificity of 98
Disadvantages
- sputum ( need to contain 5000-10000 AFB ml)
- Young children elderly amp HIV infected persons may not produce cavities amp sputum containing AFB
DrTVRao MD 16
2- Detecting AFB by fluorochrome stain using fluorescence microscopy
The smear may be stained by aura mine-O dye In this method the TB bacilli are stained yellow against dark background amp easily visualized using florescent microscope
Advantages
- More sensitive
- Rapid
Disadvantages
- Hazards of dye toxicity
- more expensive
- must be confirmed by Z-N stain
DrTVRao MD 17
LowensteinndashJensen mediumbull When grown on LJ
medium M tuberculosis appears as brown granular colonies (sometimes called buff rough and tough) The media must be incubated for a significant length of time usually four weeks due to the slow doubling time of M tuberculosis DrTVRao MD 18
3- Cultures on L J media
Lowenstein ndashJensen medium is an egg based media
with addition of salts 5 glycerol Malachite green
Advantages - Specificity about 99
- More sensitive (need lower no of bacilli 10-100 ml)
- Can differentiate between TB complex amp NTM using biochemical reactions
- Sensitivity tests for antituberculous drugs
( St INH Rif E)
Disadvantages Slowly growing ( up to 8 weeks )DrTVRao MD 19
Recent Methods for Diagnosis
I ndashBACTEC 460 ( rapid radiometric culture system )specimens are cultured in a liquid medium
(Middle brook7H9 broth base )containing C14 ndashlabelled palmitic acid amp PANTA antibiotic mixture
Growing mycobacteria utilize the acid releasing radioactive CO2 which is measured as growth index (GI) in the BACTEC instrument
The daily increase in GI output is directly proportional to the rate amp amount of growth in the medium
Mycobacteria Growth Indicator
Tube (MGIT)
Tube contains modified Middlebrook 7H9
broth base with OADC enrichment amp
PANTA antibiotic mixture
All types of clinical specimens pulmonary
as well as extra-pulmonary ( except
blood) could be cultured on this type of
media
The MGIT 960 System
The MGIT 960 system is a non-radiometeric
automated system that uses the MGIT media amp
sensors to detect the fluorescence
Advantages
-The system holds 960 plastic tubes which are
continuously monitored
- Early detection as the machine monitoring amp
reading the tubes every hour
Detection and identification of mycobacteria directly
from clinical samplesbull Genotypic Methods
bull 1048708 PCR
bull 1048708 LAMP
bull 1048708 TMA NAA
bull 1048708 Ligase chain reaction
bull 1048708 Phenotypic Methods
bull 1048708 FAST Plaque TB
DrTVRao MD 23
bull Essentially PCR is a way to make millions of identical copies of a specific DNA sequence which may be a gene or a part of a gene or simply a stretch of nucleotides with a known DNA sequence the function of which may be unknown
Polymerase Chain Reaction (PCR)
DrTVRao MD 24
Polymerase Chain Reaction (PCR) amp
Gene probeNucleic acid probes amp nucleic acid amplification
tests in which polymerase enzymes are used to
amplify ( make many copies of specific DNA or
RNA sequences extracted from mycobacterial
cells
Advantages
- Rapid procedure - High sensitivity (1-10
( 3 ndash 4 hours) bacilli ml sputum)
bull Interferon-γ assays measure cell-mediated immunity by quantifying IFN-γ released from sensitized T cells in whole bloodPBMCs incubated with TB antigens
Quantiferon-GOLD
DrTVRao MD 26
What Positive Skin Test ( Tuberculin Test means)
bull A positive TB skin test or TB blood test only tells that a person has been infected with TB bacteria It does not tell whether the person has latent TB infection (LTBI) or has progressed to TB disease
DrTVRao MD 27
Tuberculin TestInterpretation A positive test indicates previous exposure and
carriage of TB A negative tuberculin test excludes infection in
suspected persons Tuberculin positive persons may develop
reactivation type of TB Tuberculin negative persons are at risk of gaining
new infection False positive reactions are mainly due to
- Infection with nontuberculous mycobacteria
DrTVRao MD 28
False negative reactions may be due to-
bull False negative reactions may be due to
- Sever tuberculosis infection (Miliary TB) -Hodgkinrsquos disease
bull Corticosteroid therapy - Malnutrition -AIDS
bull Children below 5 years of age with no exposure history
bull Positive test must be regarded suspicious
DrTVRao MD 29
Tuberculin Test( Mantoux Test )
bull Test to be interpreted in relation to clinical evaluation
bull Even the induration of 5 mm to be considered positive when tested on HIV patients
bull Lacks specificity
Positive Test Means
bull This means the personrsquos body was infected with TB bacteria Additional tests are needed to determine if the person has latent TB infection or TB disease A health care worker will then provide treatment as needed
DrTVRao MD 31
Negative Test Means
bull This means the personrsquos body did not react to the test and that latent TB infection or TB disease is not likely
DrTVRao MD 32
Tuberculin Testing - Limitations
bull False positive reactions are mainly due to
bull - Infection with nontuberculous mycobacteria
bull False negative reactions may be due to
bull - Sever tuberculosis infection (Miliary TB) -Hodgkinrsquos disease
bull - Corticosteroid therapy - Malnutrition -AIDS
bull Children below 5 years of age with no exposure history
bull - Positive test must be regarded suspicious DrTVRao MD 33
Recent Methods for Diagnosis
I ndash BACTEC 460 ( rapid radiometric culture system )
Specimens are cultured in a liquid medium (Middle brook7H9 broth base )containing C14 ndash labeled palmitic acid amp PANTA antibiotic mixture
Growing mycobacteria utilize the acid releasing radioactive CO2 which is measured as growth index (GI) in the BACTEC instrument
The daily increase in GI output is directly proportional to the rate amp amount of growth in the medium
DrTVRao MD 34
TB blood testsbull TB blood tests (also called interferon-gamma
release assays or IGRAs) measure how the immune system reacts to the bacteria that cause TB An IGRA measures how strong a personrsquos immune system reacts to TB bacteria by testing the personrsquos blood in a laboratory
bull Two IGRAs are approved by the US Food and Drug Administration (FDA) and are available in the United States
DrTVRao MD 35
Positive IGRAbull This means that the
person has been infected with TB bacteria Additional tests are needed to determine if the person has latent TB infection or TB disease A health care worker will then provide treatment as needed
DrTVRao MD 36
Negative IGRA
bull This means that the personrsquos blood did not react to the test and that latent TB infection or TB disease is not likely
DrTVRao MD 37
IGRAs are the preferred method of TB infection testing for the following
People who have received bacilli ChalmettendashGueacuterin (BCG) BCG is a vaccine for TB disease People who have a difficult time returning for a second appointment to look for a reaction to the TST
There is no problem with repeated IGRAs
DrTVRao MD 38
III Polymerase Chain Reaction
(PCR) amp Gene probeNucleic acid probes amp nucleic acid amplification
tests in which polymerase enzymes are used to
amplify ( make many copies of specific DNA or
RNA sequences extracted from mycobacterial
cells
Advantages
- Rapid procedure - High sensitivity (1-10
( 3 ndash 4 hours) bacilli ml sputum)
DrTVRao MD 39
Molecular DR testing is particularly useful for
bull Patients suspected or at high risk of having drug-resistant TBvery ill patients for whom drug-susceptibility information might alter case management decisions such as patients who do not get better while taking standard first-line therapy
DrTVRao MD 40
Detection of MDR Tuberculosis
bull Very ill patients for whom drug-susceptibility information might alter case management decisions such as patients who do not get better while taking standard first-line therapy
DrTVRao MD 41
Detection of MDR Tuberculosis
bull outbreak or contact investigations when drug resistance is suspected in the source case or in some severely immunocompromised persons such as HIV-infected persons or those receiving dialysis in which knowledge of drug-susceptibility would be a significant benefit and affect preventive therapy decisions
DrTVRao MD 42
Tuberculosis and HIV infection
bull HIV association has become a threat to the developed countries too
bull HIV association will lead to rapid spread of tuberculosis
DrTVRao MD 43
HIV Considerations
bull HIV is the strongest risk factor for progression to active disease
bull HIV kills CD4+ T Helper cells which normally inhibit M tuberculosis
bull HIV interferes with PPD skin test
bull Protease inhibitors interfere with rifampin
DrTVRao MD 44
Epidemiologybull An ancient disease called as white plague
bull 13 of the world population is infected
bull 2 billion infected
bull Each year 9 lakhs to 1 million are infected
bull Poor nations phase the burnt of the disease
bull In developing world gt 4o of the population is effected
bull 15 million suffer the disease
bull 3 million are highly infective
DrTVRao MD 45
MDR tuberculosis
bull Multidrug resistant tuberculosis has become a global threat
bull In 1993 WHO declared Tuberculosis a Global emergency
bull Animals shed the bacilli in Milk humanrsquos get infected after drinking the unsterilized Milk
bull Pasteurization has reduced the incidence of Bovine tuberculosis
DrTVRao MD 46
Why Tuberculosis continues to be Important
bull Someone in the world is newly infected with TB bacilli every second
bull Overall one-third of the worlds population is currently infected with the TB bacillus
bull 5-10 of people who are infected with TB bacilli (but who are not infected with HIV) become sick or infectious at some time during their life People with HIV and TB infection are much more likely to develop TB
DrTVRao MD 47
bull Programme Created by DrTVRao MD for Medical and Paramedical
Students in Developing world
bull Email
bull doctortvraogmailcom
DrTVRao MD 48
![Page 6: Diagnosis of tuberculosis an Update](https://reader031.fdocuments.in/reader031/viewer/2022032113/55a62b711a28abd5138b48bb/html5/thumbnails/6.jpg)
Who Should Get Tested for TB
bull People from a country where TB disease is common (most countries in Latin America the Caribbean Africa Asia Eastern Europe and Russia)
bull People who live or work somewhere in the United States where TB disease is more common (homeless shelters prison or jails or some nursing homes)
bull People who use illegal drugsDrTVRao MD 6
X ray of Chest a Commonly used Diagnostic tool
bull Acute pulmonary TB can be easily seen on an X-ray However the picture it presents is not specific and a normal chest X-ray cannot exclude extrapulmonary TB Also in countries where resources are more limited there is often a lack of X-ray facilitiesDrTVRao MD 7
Other testsbull Other tests such
as a chest x-ray and a sample of sputum are needed to see whether the person has TB disease
DrTVRao MD 8
Types of specimens-Sputum
- BAL
-Pleural effusions
- Urine
- Stool
-CSF
-Aspiration ( gastric ndash cold abscess)
- Blood in case of haematogenous TB
DrTVRao MD 9
Laboratory Diagnosis
1- Sputum smears stained by Z-N stain
Three morning successive mucopurulent sputum samples are needed to diagnose pulmonary TB
Advantage - cheap ndash rapid
- Easy to perform
- High predictive value gt 90
- Specificity of 98
Disadvantages
- sputum ( need to contain 5000-10000 AFB ml)
- Young children elderly amp HIV infected persons may not produce cavities amp sputum containing AFB
Sputum Collectionbull Sputum specimens
are essential to confirm TBndash Specimens should be
from lung secretions not saliva
bull Collect 3 specimens on 3 different days
bull Spontaneous morning sputum more desirable than induced specimens
bull Collect sputum before treatment is initiated
11
Interpretation of sputum stained by
Z N Stain (WHO )
More than 10 bacilli field ------- +++
From 1 ndash 10 bacilli field ------- ++
From 10 ndash 99 bacilli 100 fields ----- +
From 1 -9 bacilli100 fields ------ write the no
No bacilli seen ---------- negative
2- Detecting AFB by fluorochrome stain using fluorescence microscopy
The smear may be stained by auramine-O dye In this method the TB bacilli are stained yellow against dark background amp easily visualized using florescent microscope
Advantages
- More sensitive
- Rapid
Disadvantages
- Hazards of dye toxicity
- more expensive
- must be confirmed by Z-N stain
Acid Fast Bacilli under Fluorescent Microscope
DrTVRao MD 14
Culturebull Used to confirm
diagnosis of TB
bull Culture all
specimens even if
smear is negative
bull Initial drug isolate
should be used to
determine drug
susceptibility15
Laboratory Diagnosis
1- Sputum smears stained by Z-N stain
Three morning successive mucopurulent sputum samples are needed to diagnose pulmonary TB
Advantage - cheap ndash rapid
- Easy to perform
- High predictive value gt 90
- Specificity of 98
Disadvantages
- sputum ( need to contain 5000-10000 AFB ml)
- Young children elderly amp HIV infected persons may not produce cavities amp sputum containing AFB
DrTVRao MD 16
2- Detecting AFB by fluorochrome stain using fluorescence microscopy
The smear may be stained by aura mine-O dye In this method the TB bacilli are stained yellow against dark background amp easily visualized using florescent microscope
Advantages
- More sensitive
- Rapid
Disadvantages
- Hazards of dye toxicity
- more expensive
- must be confirmed by Z-N stain
DrTVRao MD 17
LowensteinndashJensen mediumbull When grown on LJ
medium M tuberculosis appears as brown granular colonies (sometimes called buff rough and tough) The media must be incubated for a significant length of time usually four weeks due to the slow doubling time of M tuberculosis DrTVRao MD 18
3- Cultures on L J media
Lowenstein ndashJensen medium is an egg based media
with addition of salts 5 glycerol Malachite green
Advantages - Specificity about 99
- More sensitive (need lower no of bacilli 10-100 ml)
- Can differentiate between TB complex amp NTM using biochemical reactions
- Sensitivity tests for antituberculous drugs
( St INH Rif E)
Disadvantages Slowly growing ( up to 8 weeks )DrTVRao MD 19
Recent Methods for Diagnosis
I ndashBACTEC 460 ( rapid radiometric culture system )specimens are cultured in a liquid medium
(Middle brook7H9 broth base )containing C14 ndashlabelled palmitic acid amp PANTA antibiotic mixture
Growing mycobacteria utilize the acid releasing radioactive CO2 which is measured as growth index (GI) in the BACTEC instrument
The daily increase in GI output is directly proportional to the rate amp amount of growth in the medium
Mycobacteria Growth Indicator
Tube (MGIT)
Tube contains modified Middlebrook 7H9
broth base with OADC enrichment amp
PANTA antibiotic mixture
All types of clinical specimens pulmonary
as well as extra-pulmonary ( except
blood) could be cultured on this type of
media
The MGIT 960 System
The MGIT 960 system is a non-radiometeric
automated system that uses the MGIT media amp
sensors to detect the fluorescence
Advantages
-The system holds 960 plastic tubes which are
continuously monitored
- Early detection as the machine monitoring amp
reading the tubes every hour
Detection and identification of mycobacteria directly
from clinical samplesbull Genotypic Methods
bull 1048708 PCR
bull 1048708 LAMP
bull 1048708 TMA NAA
bull 1048708 Ligase chain reaction
bull 1048708 Phenotypic Methods
bull 1048708 FAST Plaque TB
DrTVRao MD 23
bull Essentially PCR is a way to make millions of identical copies of a specific DNA sequence which may be a gene or a part of a gene or simply a stretch of nucleotides with a known DNA sequence the function of which may be unknown
Polymerase Chain Reaction (PCR)
DrTVRao MD 24
Polymerase Chain Reaction (PCR) amp
Gene probeNucleic acid probes amp nucleic acid amplification
tests in which polymerase enzymes are used to
amplify ( make many copies of specific DNA or
RNA sequences extracted from mycobacterial
cells
Advantages
- Rapid procedure - High sensitivity (1-10
( 3 ndash 4 hours) bacilli ml sputum)
bull Interferon-γ assays measure cell-mediated immunity by quantifying IFN-γ released from sensitized T cells in whole bloodPBMCs incubated with TB antigens
Quantiferon-GOLD
DrTVRao MD 26
What Positive Skin Test ( Tuberculin Test means)
bull A positive TB skin test or TB blood test only tells that a person has been infected with TB bacteria It does not tell whether the person has latent TB infection (LTBI) or has progressed to TB disease
DrTVRao MD 27
Tuberculin TestInterpretation A positive test indicates previous exposure and
carriage of TB A negative tuberculin test excludes infection in
suspected persons Tuberculin positive persons may develop
reactivation type of TB Tuberculin negative persons are at risk of gaining
new infection False positive reactions are mainly due to
- Infection with nontuberculous mycobacteria
DrTVRao MD 28
False negative reactions may be due to-
bull False negative reactions may be due to
- Sever tuberculosis infection (Miliary TB) -Hodgkinrsquos disease
bull Corticosteroid therapy - Malnutrition -AIDS
bull Children below 5 years of age with no exposure history
bull Positive test must be regarded suspicious
DrTVRao MD 29
Tuberculin Test( Mantoux Test )
bull Test to be interpreted in relation to clinical evaluation
bull Even the induration of 5 mm to be considered positive when tested on HIV patients
bull Lacks specificity
Positive Test Means
bull This means the personrsquos body was infected with TB bacteria Additional tests are needed to determine if the person has latent TB infection or TB disease A health care worker will then provide treatment as needed
DrTVRao MD 31
Negative Test Means
bull This means the personrsquos body did not react to the test and that latent TB infection or TB disease is not likely
DrTVRao MD 32
Tuberculin Testing - Limitations
bull False positive reactions are mainly due to
bull - Infection with nontuberculous mycobacteria
bull False negative reactions may be due to
bull - Sever tuberculosis infection (Miliary TB) -Hodgkinrsquos disease
bull - Corticosteroid therapy - Malnutrition -AIDS
bull Children below 5 years of age with no exposure history
bull - Positive test must be regarded suspicious DrTVRao MD 33
Recent Methods for Diagnosis
I ndash BACTEC 460 ( rapid radiometric culture system )
Specimens are cultured in a liquid medium (Middle brook7H9 broth base )containing C14 ndash labeled palmitic acid amp PANTA antibiotic mixture
Growing mycobacteria utilize the acid releasing radioactive CO2 which is measured as growth index (GI) in the BACTEC instrument
The daily increase in GI output is directly proportional to the rate amp amount of growth in the medium
DrTVRao MD 34
TB blood testsbull TB blood tests (also called interferon-gamma
release assays or IGRAs) measure how the immune system reacts to the bacteria that cause TB An IGRA measures how strong a personrsquos immune system reacts to TB bacteria by testing the personrsquos blood in a laboratory
bull Two IGRAs are approved by the US Food and Drug Administration (FDA) and are available in the United States
DrTVRao MD 35
Positive IGRAbull This means that the
person has been infected with TB bacteria Additional tests are needed to determine if the person has latent TB infection or TB disease A health care worker will then provide treatment as needed
DrTVRao MD 36
Negative IGRA
bull This means that the personrsquos blood did not react to the test and that latent TB infection or TB disease is not likely
DrTVRao MD 37
IGRAs are the preferred method of TB infection testing for the following
People who have received bacilli ChalmettendashGueacuterin (BCG) BCG is a vaccine for TB disease People who have a difficult time returning for a second appointment to look for a reaction to the TST
There is no problem with repeated IGRAs
DrTVRao MD 38
III Polymerase Chain Reaction
(PCR) amp Gene probeNucleic acid probes amp nucleic acid amplification
tests in which polymerase enzymes are used to
amplify ( make many copies of specific DNA or
RNA sequences extracted from mycobacterial
cells
Advantages
- Rapid procedure - High sensitivity (1-10
( 3 ndash 4 hours) bacilli ml sputum)
DrTVRao MD 39
Molecular DR testing is particularly useful for
bull Patients suspected or at high risk of having drug-resistant TBvery ill patients for whom drug-susceptibility information might alter case management decisions such as patients who do not get better while taking standard first-line therapy
DrTVRao MD 40
Detection of MDR Tuberculosis
bull Very ill patients for whom drug-susceptibility information might alter case management decisions such as patients who do not get better while taking standard first-line therapy
DrTVRao MD 41
Detection of MDR Tuberculosis
bull outbreak or contact investigations when drug resistance is suspected in the source case or in some severely immunocompromised persons such as HIV-infected persons or those receiving dialysis in which knowledge of drug-susceptibility would be a significant benefit and affect preventive therapy decisions
DrTVRao MD 42
Tuberculosis and HIV infection
bull HIV association has become a threat to the developed countries too
bull HIV association will lead to rapid spread of tuberculosis
DrTVRao MD 43
HIV Considerations
bull HIV is the strongest risk factor for progression to active disease
bull HIV kills CD4+ T Helper cells which normally inhibit M tuberculosis
bull HIV interferes with PPD skin test
bull Protease inhibitors interfere with rifampin
DrTVRao MD 44
Epidemiologybull An ancient disease called as white plague
bull 13 of the world population is infected
bull 2 billion infected
bull Each year 9 lakhs to 1 million are infected
bull Poor nations phase the burnt of the disease
bull In developing world gt 4o of the population is effected
bull 15 million suffer the disease
bull 3 million are highly infective
DrTVRao MD 45
MDR tuberculosis
bull Multidrug resistant tuberculosis has become a global threat
bull In 1993 WHO declared Tuberculosis a Global emergency
bull Animals shed the bacilli in Milk humanrsquos get infected after drinking the unsterilized Milk
bull Pasteurization has reduced the incidence of Bovine tuberculosis
DrTVRao MD 46
Why Tuberculosis continues to be Important
bull Someone in the world is newly infected with TB bacilli every second
bull Overall one-third of the worlds population is currently infected with the TB bacillus
bull 5-10 of people who are infected with TB bacilli (but who are not infected with HIV) become sick or infectious at some time during their life People with HIV and TB infection are much more likely to develop TB
DrTVRao MD 47
bull Programme Created by DrTVRao MD for Medical and Paramedical
Students in Developing world
bull Email
bull doctortvraogmailcom
DrTVRao MD 48
![Page 7: Diagnosis of tuberculosis an Update](https://reader031.fdocuments.in/reader031/viewer/2022032113/55a62b711a28abd5138b48bb/html5/thumbnails/7.jpg)
X ray of Chest a Commonly used Diagnostic tool
bull Acute pulmonary TB can be easily seen on an X-ray However the picture it presents is not specific and a normal chest X-ray cannot exclude extrapulmonary TB Also in countries where resources are more limited there is often a lack of X-ray facilitiesDrTVRao MD 7
Other testsbull Other tests such
as a chest x-ray and a sample of sputum are needed to see whether the person has TB disease
DrTVRao MD 8
Types of specimens-Sputum
- BAL
-Pleural effusions
- Urine
- Stool
-CSF
-Aspiration ( gastric ndash cold abscess)
- Blood in case of haematogenous TB
DrTVRao MD 9
Laboratory Diagnosis
1- Sputum smears stained by Z-N stain
Three morning successive mucopurulent sputum samples are needed to diagnose pulmonary TB
Advantage - cheap ndash rapid
- Easy to perform
- High predictive value gt 90
- Specificity of 98
Disadvantages
- sputum ( need to contain 5000-10000 AFB ml)
- Young children elderly amp HIV infected persons may not produce cavities amp sputum containing AFB
Sputum Collectionbull Sputum specimens
are essential to confirm TBndash Specimens should be
from lung secretions not saliva
bull Collect 3 specimens on 3 different days
bull Spontaneous morning sputum more desirable than induced specimens
bull Collect sputum before treatment is initiated
11
Interpretation of sputum stained by
Z N Stain (WHO )
More than 10 bacilli field ------- +++
From 1 ndash 10 bacilli field ------- ++
From 10 ndash 99 bacilli 100 fields ----- +
From 1 -9 bacilli100 fields ------ write the no
No bacilli seen ---------- negative
2- Detecting AFB by fluorochrome stain using fluorescence microscopy
The smear may be stained by auramine-O dye In this method the TB bacilli are stained yellow against dark background amp easily visualized using florescent microscope
Advantages
- More sensitive
- Rapid
Disadvantages
- Hazards of dye toxicity
- more expensive
- must be confirmed by Z-N stain
Acid Fast Bacilli under Fluorescent Microscope
DrTVRao MD 14
Culturebull Used to confirm
diagnosis of TB
bull Culture all
specimens even if
smear is negative
bull Initial drug isolate
should be used to
determine drug
susceptibility15
Laboratory Diagnosis
1- Sputum smears stained by Z-N stain
Three morning successive mucopurulent sputum samples are needed to diagnose pulmonary TB
Advantage - cheap ndash rapid
- Easy to perform
- High predictive value gt 90
- Specificity of 98
Disadvantages
- sputum ( need to contain 5000-10000 AFB ml)
- Young children elderly amp HIV infected persons may not produce cavities amp sputum containing AFB
DrTVRao MD 16
2- Detecting AFB by fluorochrome stain using fluorescence microscopy
The smear may be stained by aura mine-O dye In this method the TB bacilli are stained yellow against dark background amp easily visualized using florescent microscope
Advantages
- More sensitive
- Rapid
Disadvantages
- Hazards of dye toxicity
- more expensive
- must be confirmed by Z-N stain
DrTVRao MD 17
LowensteinndashJensen mediumbull When grown on LJ
medium M tuberculosis appears as brown granular colonies (sometimes called buff rough and tough) The media must be incubated for a significant length of time usually four weeks due to the slow doubling time of M tuberculosis DrTVRao MD 18
3- Cultures on L J media
Lowenstein ndashJensen medium is an egg based media
with addition of salts 5 glycerol Malachite green
Advantages - Specificity about 99
- More sensitive (need lower no of bacilli 10-100 ml)
- Can differentiate between TB complex amp NTM using biochemical reactions
- Sensitivity tests for antituberculous drugs
( St INH Rif E)
Disadvantages Slowly growing ( up to 8 weeks )DrTVRao MD 19
Recent Methods for Diagnosis
I ndashBACTEC 460 ( rapid radiometric culture system )specimens are cultured in a liquid medium
(Middle brook7H9 broth base )containing C14 ndashlabelled palmitic acid amp PANTA antibiotic mixture
Growing mycobacteria utilize the acid releasing radioactive CO2 which is measured as growth index (GI) in the BACTEC instrument
The daily increase in GI output is directly proportional to the rate amp amount of growth in the medium
Mycobacteria Growth Indicator
Tube (MGIT)
Tube contains modified Middlebrook 7H9
broth base with OADC enrichment amp
PANTA antibiotic mixture
All types of clinical specimens pulmonary
as well as extra-pulmonary ( except
blood) could be cultured on this type of
media
The MGIT 960 System
The MGIT 960 system is a non-radiometeric
automated system that uses the MGIT media amp
sensors to detect the fluorescence
Advantages
-The system holds 960 plastic tubes which are
continuously monitored
- Early detection as the machine monitoring amp
reading the tubes every hour
Detection and identification of mycobacteria directly
from clinical samplesbull Genotypic Methods
bull 1048708 PCR
bull 1048708 LAMP
bull 1048708 TMA NAA
bull 1048708 Ligase chain reaction
bull 1048708 Phenotypic Methods
bull 1048708 FAST Plaque TB
DrTVRao MD 23
bull Essentially PCR is a way to make millions of identical copies of a specific DNA sequence which may be a gene or a part of a gene or simply a stretch of nucleotides with a known DNA sequence the function of which may be unknown
Polymerase Chain Reaction (PCR)
DrTVRao MD 24
Polymerase Chain Reaction (PCR) amp
Gene probeNucleic acid probes amp nucleic acid amplification
tests in which polymerase enzymes are used to
amplify ( make many copies of specific DNA or
RNA sequences extracted from mycobacterial
cells
Advantages
- Rapid procedure - High sensitivity (1-10
( 3 ndash 4 hours) bacilli ml sputum)
bull Interferon-γ assays measure cell-mediated immunity by quantifying IFN-γ released from sensitized T cells in whole bloodPBMCs incubated with TB antigens
Quantiferon-GOLD
DrTVRao MD 26
What Positive Skin Test ( Tuberculin Test means)
bull A positive TB skin test or TB blood test only tells that a person has been infected with TB bacteria It does not tell whether the person has latent TB infection (LTBI) or has progressed to TB disease
DrTVRao MD 27
Tuberculin TestInterpretation A positive test indicates previous exposure and
carriage of TB A negative tuberculin test excludes infection in
suspected persons Tuberculin positive persons may develop
reactivation type of TB Tuberculin negative persons are at risk of gaining
new infection False positive reactions are mainly due to
- Infection with nontuberculous mycobacteria
DrTVRao MD 28
False negative reactions may be due to-
bull False negative reactions may be due to
- Sever tuberculosis infection (Miliary TB) -Hodgkinrsquos disease
bull Corticosteroid therapy - Malnutrition -AIDS
bull Children below 5 years of age with no exposure history
bull Positive test must be regarded suspicious
DrTVRao MD 29
Tuberculin Test( Mantoux Test )
bull Test to be interpreted in relation to clinical evaluation
bull Even the induration of 5 mm to be considered positive when tested on HIV patients
bull Lacks specificity
Positive Test Means
bull This means the personrsquos body was infected with TB bacteria Additional tests are needed to determine if the person has latent TB infection or TB disease A health care worker will then provide treatment as needed
DrTVRao MD 31
Negative Test Means
bull This means the personrsquos body did not react to the test and that latent TB infection or TB disease is not likely
DrTVRao MD 32
Tuberculin Testing - Limitations
bull False positive reactions are mainly due to
bull - Infection with nontuberculous mycobacteria
bull False negative reactions may be due to
bull - Sever tuberculosis infection (Miliary TB) -Hodgkinrsquos disease
bull - Corticosteroid therapy - Malnutrition -AIDS
bull Children below 5 years of age with no exposure history
bull - Positive test must be regarded suspicious DrTVRao MD 33
Recent Methods for Diagnosis
I ndash BACTEC 460 ( rapid radiometric culture system )
Specimens are cultured in a liquid medium (Middle brook7H9 broth base )containing C14 ndash labeled palmitic acid amp PANTA antibiotic mixture
Growing mycobacteria utilize the acid releasing radioactive CO2 which is measured as growth index (GI) in the BACTEC instrument
The daily increase in GI output is directly proportional to the rate amp amount of growth in the medium
DrTVRao MD 34
TB blood testsbull TB blood tests (also called interferon-gamma
release assays or IGRAs) measure how the immune system reacts to the bacteria that cause TB An IGRA measures how strong a personrsquos immune system reacts to TB bacteria by testing the personrsquos blood in a laboratory
bull Two IGRAs are approved by the US Food and Drug Administration (FDA) and are available in the United States
DrTVRao MD 35
Positive IGRAbull This means that the
person has been infected with TB bacteria Additional tests are needed to determine if the person has latent TB infection or TB disease A health care worker will then provide treatment as needed
DrTVRao MD 36
Negative IGRA
bull This means that the personrsquos blood did not react to the test and that latent TB infection or TB disease is not likely
DrTVRao MD 37
IGRAs are the preferred method of TB infection testing for the following
People who have received bacilli ChalmettendashGueacuterin (BCG) BCG is a vaccine for TB disease People who have a difficult time returning for a second appointment to look for a reaction to the TST
There is no problem with repeated IGRAs
DrTVRao MD 38
III Polymerase Chain Reaction
(PCR) amp Gene probeNucleic acid probes amp nucleic acid amplification
tests in which polymerase enzymes are used to
amplify ( make many copies of specific DNA or
RNA sequences extracted from mycobacterial
cells
Advantages
- Rapid procedure - High sensitivity (1-10
( 3 ndash 4 hours) bacilli ml sputum)
DrTVRao MD 39
Molecular DR testing is particularly useful for
bull Patients suspected or at high risk of having drug-resistant TBvery ill patients for whom drug-susceptibility information might alter case management decisions such as patients who do not get better while taking standard first-line therapy
DrTVRao MD 40
Detection of MDR Tuberculosis
bull Very ill patients for whom drug-susceptibility information might alter case management decisions such as patients who do not get better while taking standard first-line therapy
DrTVRao MD 41
Detection of MDR Tuberculosis
bull outbreak or contact investigations when drug resistance is suspected in the source case or in some severely immunocompromised persons such as HIV-infected persons or those receiving dialysis in which knowledge of drug-susceptibility would be a significant benefit and affect preventive therapy decisions
DrTVRao MD 42
Tuberculosis and HIV infection
bull HIV association has become a threat to the developed countries too
bull HIV association will lead to rapid spread of tuberculosis
DrTVRao MD 43
HIV Considerations
bull HIV is the strongest risk factor for progression to active disease
bull HIV kills CD4+ T Helper cells which normally inhibit M tuberculosis
bull HIV interferes with PPD skin test
bull Protease inhibitors interfere with rifampin
DrTVRao MD 44
Epidemiologybull An ancient disease called as white plague
bull 13 of the world population is infected
bull 2 billion infected
bull Each year 9 lakhs to 1 million are infected
bull Poor nations phase the burnt of the disease
bull In developing world gt 4o of the population is effected
bull 15 million suffer the disease
bull 3 million are highly infective
DrTVRao MD 45
MDR tuberculosis
bull Multidrug resistant tuberculosis has become a global threat
bull In 1993 WHO declared Tuberculosis a Global emergency
bull Animals shed the bacilli in Milk humanrsquos get infected after drinking the unsterilized Milk
bull Pasteurization has reduced the incidence of Bovine tuberculosis
DrTVRao MD 46
Why Tuberculosis continues to be Important
bull Someone in the world is newly infected with TB bacilli every second
bull Overall one-third of the worlds population is currently infected with the TB bacillus
bull 5-10 of people who are infected with TB bacilli (but who are not infected with HIV) become sick or infectious at some time during their life People with HIV and TB infection are much more likely to develop TB
DrTVRao MD 47
bull Programme Created by DrTVRao MD for Medical and Paramedical
Students in Developing world
bull Email
bull doctortvraogmailcom
DrTVRao MD 48
![Page 8: Diagnosis of tuberculosis an Update](https://reader031.fdocuments.in/reader031/viewer/2022032113/55a62b711a28abd5138b48bb/html5/thumbnails/8.jpg)
Other testsbull Other tests such
as a chest x-ray and a sample of sputum are needed to see whether the person has TB disease
DrTVRao MD 8
Types of specimens-Sputum
- BAL
-Pleural effusions
- Urine
- Stool
-CSF
-Aspiration ( gastric ndash cold abscess)
- Blood in case of haematogenous TB
DrTVRao MD 9
Laboratory Diagnosis
1- Sputum smears stained by Z-N stain
Three morning successive mucopurulent sputum samples are needed to diagnose pulmonary TB
Advantage - cheap ndash rapid
- Easy to perform
- High predictive value gt 90
- Specificity of 98
Disadvantages
- sputum ( need to contain 5000-10000 AFB ml)
- Young children elderly amp HIV infected persons may not produce cavities amp sputum containing AFB
Sputum Collectionbull Sputum specimens
are essential to confirm TBndash Specimens should be
from lung secretions not saliva
bull Collect 3 specimens on 3 different days
bull Spontaneous morning sputum more desirable than induced specimens
bull Collect sputum before treatment is initiated
11
Interpretation of sputum stained by
Z N Stain (WHO )
More than 10 bacilli field ------- +++
From 1 ndash 10 bacilli field ------- ++
From 10 ndash 99 bacilli 100 fields ----- +
From 1 -9 bacilli100 fields ------ write the no
No bacilli seen ---------- negative
2- Detecting AFB by fluorochrome stain using fluorescence microscopy
The smear may be stained by auramine-O dye In this method the TB bacilli are stained yellow against dark background amp easily visualized using florescent microscope
Advantages
- More sensitive
- Rapid
Disadvantages
- Hazards of dye toxicity
- more expensive
- must be confirmed by Z-N stain
Acid Fast Bacilli under Fluorescent Microscope
DrTVRao MD 14
Culturebull Used to confirm
diagnosis of TB
bull Culture all
specimens even if
smear is negative
bull Initial drug isolate
should be used to
determine drug
susceptibility15
Laboratory Diagnosis
1- Sputum smears stained by Z-N stain
Three morning successive mucopurulent sputum samples are needed to diagnose pulmonary TB
Advantage - cheap ndash rapid
- Easy to perform
- High predictive value gt 90
- Specificity of 98
Disadvantages
- sputum ( need to contain 5000-10000 AFB ml)
- Young children elderly amp HIV infected persons may not produce cavities amp sputum containing AFB
DrTVRao MD 16
2- Detecting AFB by fluorochrome stain using fluorescence microscopy
The smear may be stained by aura mine-O dye In this method the TB bacilli are stained yellow against dark background amp easily visualized using florescent microscope
Advantages
- More sensitive
- Rapid
Disadvantages
- Hazards of dye toxicity
- more expensive
- must be confirmed by Z-N stain
DrTVRao MD 17
LowensteinndashJensen mediumbull When grown on LJ
medium M tuberculosis appears as brown granular colonies (sometimes called buff rough and tough) The media must be incubated for a significant length of time usually four weeks due to the slow doubling time of M tuberculosis DrTVRao MD 18
3- Cultures on L J media
Lowenstein ndashJensen medium is an egg based media
with addition of salts 5 glycerol Malachite green
Advantages - Specificity about 99
- More sensitive (need lower no of bacilli 10-100 ml)
- Can differentiate between TB complex amp NTM using biochemical reactions
- Sensitivity tests for antituberculous drugs
( St INH Rif E)
Disadvantages Slowly growing ( up to 8 weeks )DrTVRao MD 19
Recent Methods for Diagnosis
I ndashBACTEC 460 ( rapid radiometric culture system )specimens are cultured in a liquid medium
(Middle brook7H9 broth base )containing C14 ndashlabelled palmitic acid amp PANTA antibiotic mixture
Growing mycobacteria utilize the acid releasing radioactive CO2 which is measured as growth index (GI) in the BACTEC instrument
The daily increase in GI output is directly proportional to the rate amp amount of growth in the medium
Mycobacteria Growth Indicator
Tube (MGIT)
Tube contains modified Middlebrook 7H9
broth base with OADC enrichment amp
PANTA antibiotic mixture
All types of clinical specimens pulmonary
as well as extra-pulmonary ( except
blood) could be cultured on this type of
media
The MGIT 960 System
The MGIT 960 system is a non-radiometeric
automated system that uses the MGIT media amp
sensors to detect the fluorescence
Advantages
-The system holds 960 plastic tubes which are
continuously monitored
- Early detection as the machine monitoring amp
reading the tubes every hour
Detection and identification of mycobacteria directly
from clinical samplesbull Genotypic Methods
bull 1048708 PCR
bull 1048708 LAMP
bull 1048708 TMA NAA
bull 1048708 Ligase chain reaction
bull 1048708 Phenotypic Methods
bull 1048708 FAST Plaque TB
DrTVRao MD 23
bull Essentially PCR is a way to make millions of identical copies of a specific DNA sequence which may be a gene or a part of a gene or simply a stretch of nucleotides with a known DNA sequence the function of which may be unknown
Polymerase Chain Reaction (PCR)
DrTVRao MD 24
Polymerase Chain Reaction (PCR) amp
Gene probeNucleic acid probes amp nucleic acid amplification
tests in which polymerase enzymes are used to
amplify ( make many copies of specific DNA or
RNA sequences extracted from mycobacterial
cells
Advantages
- Rapid procedure - High sensitivity (1-10
( 3 ndash 4 hours) bacilli ml sputum)
bull Interferon-γ assays measure cell-mediated immunity by quantifying IFN-γ released from sensitized T cells in whole bloodPBMCs incubated with TB antigens
Quantiferon-GOLD
DrTVRao MD 26
What Positive Skin Test ( Tuberculin Test means)
bull A positive TB skin test or TB blood test only tells that a person has been infected with TB bacteria It does not tell whether the person has latent TB infection (LTBI) or has progressed to TB disease
DrTVRao MD 27
Tuberculin TestInterpretation A positive test indicates previous exposure and
carriage of TB A negative tuberculin test excludes infection in
suspected persons Tuberculin positive persons may develop
reactivation type of TB Tuberculin negative persons are at risk of gaining
new infection False positive reactions are mainly due to
- Infection with nontuberculous mycobacteria
DrTVRao MD 28
False negative reactions may be due to-
bull False negative reactions may be due to
- Sever tuberculosis infection (Miliary TB) -Hodgkinrsquos disease
bull Corticosteroid therapy - Malnutrition -AIDS
bull Children below 5 years of age with no exposure history
bull Positive test must be regarded suspicious
DrTVRao MD 29
Tuberculin Test( Mantoux Test )
bull Test to be interpreted in relation to clinical evaluation
bull Even the induration of 5 mm to be considered positive when tested on HIV patients
bull Lacks specificity
Positive Test Means
bull This means the personrsquos body was infected with TB bacteria Additional tests are needed to determine if the person has latent TB infection or TB disease A health care worker will then provide treatment as needed
DrTVRao MD 31
Negative Test Means
bull This means the personrsquos body did not react to the test and that latent TB infection or TB disease is not likely
DrTVRao MD 32
Tuberculin Testing - Limitations
bull False positive reactions are mainly due to
bull - Infection with nontuberculous mycobacteria
bull False negative reactions may be due to
bull - Sever tuberculosis infection (Miliary TB) -Hodgkinrsquos disease
bull - Corticosteroid therapy - Malnutrition -AIDS
bull Children below 5 years of age with no exposure history
bull - Positive test must be regarded suspicious DrTVRao MD 33
Recent Methods for Diagnosis
I ndash BACTEC 460 ( rapid radiometric culture system )
Specimens are cultured in a liquid medium (Middle brook7H9 broth base )containing C14 ndash labeled palmitic acid amp PANTA antibiotic mixture
Growing mycobacteria utilize the acid releasing radioactive CO2 which is measured as growth index (GI) in the BACTEC instrument
The daily increase in GI output is directly proportional to the rate amp amount of growth in the medium
DrTVRao MD 34
TB blood testsbull TB blood tests (also called interferon-gamma
release assays or IGRAs) measure how the immune system reacts to the bacteria that cause TB An IGRA measures how strong a personrsquos immune system reacts to TB bacteria by testing the personrsquos blood in a laboratory
bull Two IGRAs are approved by the US Food and Drug Administration (FDA) and are available in the United States
DrTVRao MD 35
Positive IGRAbull This means that the
person has been infected with TB bacteria Additional tests are needed to determine if the person has latent TB infection or TB disease A health care worker will then provide treatment as needed
DrTVRao MD 36
Negative IGRA
bull This means that the personrsquos blood did not react to the test and that latent TB infection or TB disease is not likely
DrTVRao MD 37
IGRAs are the preferred method of TB infection testing for the following
People who have received bacilli ChalmettendashGueacuterin (BCG) BCG is a vaccine for TB disease People who have a difficult time returning for a second appointment to look for a reaction to the TST
There is no problem with repeated IGRAs
DrTVRao MD 38
III Polymerase Chain Reaction
(PCR) amp Gene probeNucleic acid probes amp nucleic acid amplification
tests in which polymerase enzymes are used to
amplify ( make many copies of specific DNA or
RNA sequences extracted from mycobacterial
cells
Advantages
- Rapid procedure - High sensitivity (1-10
( 3 ndash 4 hours) bacilli ml sputum)
DrTVRao MD 39
Molecular DR testing is particularly useful for
bull Patients suspected or at high risk of having drug-resistant TBvery ill patients for whom drug-susceptibility information might alter case management decisions such as patients who do not get better while taking standard first-line therapy
DrTVRao MD 40
Detection of MDR Tuberculosis
bull Very ill patients for whom drug-susceptibility information might alter case management decisions such as patients who do not get better while taking standard first-line therapy
DrTVRao MD 41
Detection of MDR Tuberculosis
bull outbreak or contact investigations when drug resistance is suspected in the source case or in some severely immunocompromised persons such as HIV-infected persons or those receiving dialysis in which knowledge of drug-susceptibility would be a significant benefit and affect preventive therapy decisions
DrTVRao MD 42
Tuberculosis and HIV infection
bull HIV association has become a threat to the developed countries too
bull HIV association will lead to rapid spread of tuberculosis
DrTVRao MD 43
HIV Considerations
bull HIV is the strongest risk factor for progression to active disease
bull HIV kills CD4+ T Helper cells which normally inhibit M tuberculosis
bull HIV interferes with PPD skin test
bull Protease inhibitors interfere with rifampin
DrTVRao MD 44
Epidemiologybull An ancient disease called as white plague
bull 13 of the world population is infected
bull 2 billion infected
bull Each year 9 lakhs to 1 million are infected
bull Poor nations phase the burnt of the disease
bull In developing world gt 4o of the population is effected
bull 15 million suffer the disease
bull 3 million are highly infective
DrTVRao MD 45
MDR tuberculosis
bull Multidrug resistant tuberculosis has become a global threat
bull In 1993 WHO declared Tuberculosis a Global emergency
bull Animals shed the bacilli in Milk humanrsquos get infected after drinking the unsterilized Milk
bull Pasteurization has reduced the incidence of Bovine tuberculosis
DrTVRao MD 46
Why Tuberculosis continues to be Important
bull Someone in the world is newly infected with TB bacilli every second
bull Overall one-third of the worlds population is currently infected with the TB bacillus
bull 5-10 of people who are infected with TB bacilli (but who are not infected with HIV) become sick or infectious at some time during their life People with HIV and TB infection are much more likely to develop TB
DrTVRao MD 47
bull Programme Created by DrTVRao MD for Medical and Paramedical
Students in Developing world
bull Email
bull doctortvraogmailcom
DrTVRao MD 48
![Page 9: Diagnosis of tuberculosis an Update](https://reader031.fdocuments.in/reader031/viewer/2022032113/55a62b711a28abd5138b48bb/html5/thumbnails/9.jpg)
Types of specimens-Sputum
- BAL
-Pleural effusions
- Urine
- Stool
-CSF
-Aspiration ( gastric ndash cold abscess)
- Blood in case of haematogenous TB
DrTVRao MD 9
Laboratory Diagnosis
1- Sputum smears stained by Z-N stain
Three morning successive mucopurulent sputum samples are needed to diagnose pulmonary TB
Advantage - cheap ndash rapid
- Easy to perform
- High predictive value gt 90
- Specificity of 98
Disadvantages
- sputum ( need to contain 5000-10000 AFB ml)
- Young children elderly amp HIV infected persons may not produce cavities amp sputum containing AFB
Sputum Collectionbull Sputum specimens
are essential to confirm TBndash Specimens should be
from lung secretions not saliva
bull Collect 3 specimens on 3 different days
bull Spontaneous morning sputum more desirable than induced specimens
bull Collect sputum before treatment is initiated
11
Interpretation of sputum stained by
Z N Stain (WHO )
More than 10 bacilli field ------- +++
From 1 ndash 10 bacilli field ------- ++
From 10 ndash 99 bacilli 100 fields ----- +
From 1 -9 bacilli100 fields ------ write the no
No bacilli seen ---------- negative
2- Detecting AFB by fluorochrome stain using fluorescence microscopy
The smear may be stained by auramine-O dye In this method the TB bacilli are stained yellow against dark background amp easily visualized using florescent microscope
Advantages
- More sensitive
- Rapid
Disadvantages
- Hazards of dye toxicity
- more expensive
- must be confirmed by Z-N stain
Acid Fast Bacilli under Fluorescent Microscope
DrTVRao MD 14
Culturebull Used to confirm
diagnosis of TB
bull Culture all
specimens even if
smear is negative
bull Initial drug isolate
should be used to
determine drug
susceptibility15
Laboratory Diagnosis
1- Sputum smears stained by Z-N stain
Three morning successive mucopurulent sputum samples are needed to diagnose pulmonary TB
Advantage - cheap ndash rapid
- Easy to perform
- High predictive value gt 90
- Specificity of 98
Disadvantages
- sputum ( need to contain 5000-10000 AFB ml)
- Young children elderly amp HIV infected persons may not produce cavities amp sputum containing AFB
DrTVRao MD 16
2- Detecting AFB by fluorochrome stain using fluorescence microscopy
The smear may be stained by aura mine-O dye In this method the TB bacilli are stained yellow against dark background amp easily visualized using florescent microscope
Advantages
- More sensitive
- Rapid
Disadvantages
- Hazards of dye toxicity
- more expensive
- must be confirmed by Z-N stain
DrTVRao MD 17
LowensteinndashJensen mediumbull When grown on LJ
medium M tuberculosis appears as brown granular colonies (sometimes called buff rough and tough) The media must be incubated for a significant length of time usually four weeks due to the slow doubling time of M tuberculosis DrTVRao MD 18
3- Cultures on L J media
Lowenstein ndashJensen medium is an egg based media
with addition of salts 5 glycerol Malachite green
Advantages - Specificity about 99
- More sensitive (need lower no of bacilli 10-100 ml)
- Can differentiate between TB complex amp NTM using biochemical reactions
- Sensitivity tests for antituberculous drugs
( St INH Rif E)
Disadvantages Slowly growing ( up to 8 weeks )DrTVRao MD 19
Recent Methods for Diagnosis
I ndashBACTEC 460 ( rapid radiometric culture system )specimens are cultured in a liquid medium
(Middle brook7H9 broth base )containing C14 ndashlabelled palmitic acid amp PANTA antibiotic mixture
Growing mycobacteria utilize the acid releasing radioactive CO2 which is measured as growth index (GI) in the BACTEC instrument
The daily increase in GI output is directly proportional to the rate amp amount of growth in the medium
Mycobacteria Growth Indicator
Tube (MGIT)
Tube contains modified Middlebrook 7H9
broth base with OADC enrichment amp
PANTA antibiotic mixture
All types of clinical specimens pulmonary
as well as extra-pulmonary ( except
blood) could be cultured on this type of
media
The MGIT 960 System
The MGIT 960 system is a non-radiometeric
automated system that uses the MGIT media amp
sensors to detect the fluorescence
Advantages
-The system holds 960 plastic tubes which are
continuously monitored
- Early detection as the machine monitoring amp
reading the tubes every hour
Detection and identification of mycobacteria directly
from clinical samplesbull Genotypic Methods
bull 1048708 PCR
bull 1048708 LAMP
bull 1048708 TMA NAA
bull 1048708 Ligase chain reaction
bull 1048708 Phenotypic Methods
bull 1048708 FAST Plaque TB
DrTVRao MD 23
bull Essentially PCR is a way to make millions of identical copies of a specific DNA sequence which may be a gene or a part of a gene or simply a stretch of nucleotides with a known DNA sequence the function of which may be unknown
Polymerase Chain Reaction (PCR)
DrTVRao MD 24
Polymerase Chain Reaction (PCR) amp
Gene probeNucleic acid probes amp nucleic acid amplification
tests in which polymerase enzymes are used to
amplify ( make many copies of specific DNA or
RNA sequences extracted from mycobacterial
cells
Advantages
- Rapid procedure - High sensitivity (1-10
( 3 ndash 4 hours) bacilli ml sputum)
bull Interferon-γ assays measure cell-mediated immunity by quantifying IFN-γ released from sensitized T cells in whole bloodPBMCs incubated with TB antigens
Quantiferon-GOLD
DrTVRao MD 26
What Positive Skin Test ( Tuberculin Test means)
bull A positive TB skin test or TB blood test only tells that a person has been infected with TB bacteria It does not tell whether the person has latent TB infection (LTBI) or has progressed to TB disease
DrTVRao MD 27
Tuberculin TestInterpretation A positive test indicates previous exposure and
carriage of TB A negative tuberculin test excludes infection in
suspected persons Tuberculin positive persons may develop
reactivation type of TB Tuberculin negative persons are at risk of gaining
new infection False positive reactions are mainly due to
- Infection with nontuberculous mycobacteria
DrTVRao MD 28
False negative reactions may be due to-
bull False negative reactions may be due to
- Sever tuberculosis infection (Miliary TB) -Hodgkinrsquos disease
bull Corticosteroid therapy - Malnutrition -AIDS
bull Children below 5 years of age with no exposure history
bull Positive test must be regarded suspicious
DrTVRao MD 29
Tuberculin Test( Mantoux Test )
bull Test to be interpreted in relation to clinical evaluation
bull Even the induration of 5 mm to be considered positive when tested on HIV patients
bull Lacks specificity
Positive Test Means
bull This means the personrsquos body was infected with TB bacteria Additional tests are needed to determine if the person has latent TB infection or TB disease A health care worker will then provide treatment as needed
DrTVRao MD 31
Negative Test Means
bull This means the personrsquos body did not react to the test and that latent TB infection or TB disease is not likely
DrTVRao MD 32
Tuberculin Testing - Limitations
bull False positive reactions are mainly due to
bull - Infection with nontuberculous mycobacteria
bull False negative reactions may be due to
bull - Sever tuberculosis infection (Miliary TB) -Hodgkinrsquos disease
bull - Corticosteroid therapy - Malnutrition -AIDS
bull Children below 5 years of age with no exposure history
bull - Positive test must be regarded suspicious DrTVRao MD 33
Recent Methods for Diagnosis
I ndash BACTEC 460 ( rapid radiometric culture system )
Specimens are cultured in a liquid medium (Middle brook7H9 broth base )containing C14 ndash labeled palmitic acid amp PANTA antibiotic mixture
Growing mycobacteria utilize the acid releasing radioactive CO2 which is measured as growth index (GI) in the BACTEC instrument
The daily increase in GI output is directly proportional to the rate amp amount of growth in the medium
DrTVRao MD 34
TB blood testsbull TB blood tests (also called interferon-gamma
release assays or IGRAs) measure how the immune system reacts to the bacteria that cause TB An IGRA measures how strong a personrsquos immune system reacts to TB bacteria by testing the personrsquos blood in a laboratory
bull Two IGRAs are approved by the US Food and Drug Administration (FDA) and are available in the United States
DrTVRao MD 35
Positive IGRAbull This means that the
person has been infected with TB bacteria Additional tests are needed to determine if the person has latent TB infection or TB disease A health care worker will then provide treatment as needed
DrTVRao MD 36
Negative IGRA
bull This means that the personrsquos blood did not react to the test and that latent TB infection or TB disease is not likely
DrTVRao MD 37
IGRAs are the preferred method of TB infection testing for the following
People who have received bacilli ChalmettendashGueacuterin (BCG) BCG is a vaccine for TB disease People who have a difficult time returning for a second appointment to look for a reaction to the TST
There is no problem with repeated IGRAs
DrTVRao MD 38
III Polymerase Chain Reaction
(PCR) amp Gene probeNucleic acid probes amp nucleic acid amplification
tests in which polymerase enzymes are used to
amplify ( make many copies of specific DNA or
RNA sequences extracted from mycobacterial
cells
Advantages
- Rapid procedure - High sensitivity (1-10
( 3 ndash 4 hours) bacilli ml sputum)
DrTVRao MD 39
Molecular DR testing is particularly useful for
bull Patients suspected or at high risk of having drug-resistant TBvery ill patients for whom drug-susceptibility information might alter case management decisions such as patients who do not get better while taking standard first-line therapy
DrTVRao MD 40
Detection of MDR Tuberculosis
bull Very ill patients for whom drug-susceptibility information might alter case management decisions such as patients who do not get better while taking standard first-line therapy
DrTVRao MD 41
Detection of MDR Tuberculosis
bull outbreak or contact investigations when drug resistance is suspected in the source case or in some severely immunocompromised persons such as HIV-infected persons or those receiving dialysis in which knowledge of drug-susceptibility would be a significant benefit and affect preventive therapy decisions
DrTVRao MD 42
Tuberculosis and HIV infection
bull HIV association has become a threat to the developed countries too
bull HIV association will lead to rapid spread of tuberculosis
DrTVRao MD 43
HIV Considerations
bull HIV is the strongest risk factor for progression to active disease
bull HIV kills CD4+ T Helper cells which normally inhibit M tuberculosis
bull HIV interferes with PPD skin test
bull Protease inhibitors interfere with rifampin
DrTVRao MD 44
Epidemiologybull An ancient disease called as white plague
bull 13 of the world population is infected
bull 2 billion infected
bull Each year 9 lakhs to 1 million are infected
bull Poor nations phase the burnt of the disease
bull In developing world gt 4o of the population is effected
bull 15 million suffer the disease
bull 3 million are highly infective
DrTVRao MD 45
MDR tuberculosis
bull Multidrug resistant tuberculosis has become a global threat
bull In 1993 WHO declared Tuberculosis a Global emergency
bull Animals shed the bacilli in Milk humanrsquos get infected after drinking the unsterilized Milk
bull Pasteurization has reduced the incidence of Bovine tuberculosis
DrTVRao MD 46
Why Tuberculosis continues to be Important
bull Someone in the world is newly infected with TB bacilli every second
bull Overall one-third of the worlds population is currently infected with the TB bacillus
bull 5-10 of people who are infected with TB bacilli (but who are not infected with HIV) become sick or infectious at some time during their life People with HIV and TB infection are much more likely to develop TB
DrTVRao MD 47
bull Programme Created by DrTVRao MD for Medical and Paramedical
Students in Developing world
bull Email
bull doctortvraogmailcom
DrTVRao MD 48
![Page 10: Diagnosis of tuberculosis an Update](https://reader031.fdocuments.in/reader031/viewer/2022032113/55a62b711a28abd5138b48bb/html5/thumbnails/10.jpg)
Laboratory Diagnosis
1- Sputum smears stained by Z-N stain
Three morning successive mucopurulent sputum samples are needed to diagnose pulmonary TB
Advantage - cheap ndash rapid
- Easy to perform
- High predictive value gt 90
- Specificity of 98
Disadvantages
- sputum ( need to contain 5000-10000 AFB ml)
- Young children elderly amp HIV infected persons may not produce cavities amp sputum containing AFB
Sputum Collectionbull Sputum specimens
are essential to confirm TBndash Specimens should be
from lung secretions not saliva
bull Collect 3 specimens on 3 different days
bull Spontaneous morning sputum more desirable than induced specimens
bull Collect sputum before treatment is initiated
11
Interpretation of sputum stained by
Z N Stain (WHO )
More than 10 bacilli field ------- +++
From 1 ndash 10 bacilli field ------- ++
From 10 ndash 99 bacilli 100 fields ----- +
From 1 -9 bacilli100 fields ------ write the no
No bacilli seen ---------- negative
2- Detecting AFB by fluorochrome stain using fluorescence microscopy
The smear may be stained by auramine-O dye In this method the TB bacilli are stained yellow against dark background amp easily visualized using florescent microscope
Advantages
- More sensitive
- Rapid
Disadvantages
- Hazards of dye toxicity
- more expensive
- must be confirmed by Z-N stain
Acid Fast Bacilli under Fluorescent Microscope
DrTVRao MD 14
Culturebull Used to confirm
diagnosis of TB
bull Culture all
specimens even if
smear is negative
bull Initial drug isolate
should be used to
determine drug
susceptibility15
Laboratory Diagnosis
1- Sputum smears stained by Z-N stain
Three morning successive mucopurulent sputum samples are needed to diagnose pulmonary TB
Advantage - cheap ndash rapid
- Easy to perform
- High predictive value gt 90
- Specificity of 98
Disadvantages
- sputum ( need to contain 5000-10000 AFB ml)
- Young children elderly amp HIV infected persons may not produce cavities amp sputum containing AFB
DrTVRao MD 16
2- Detecting AFB by fluorochrome stain using fluorescence microscopy
The smear may be stained by aura mine-O dye In this method the TB bacilli are stained yellow against dark background amp easily visualized using florescent microscope
Advantages
- More sensitive
- Rapid
Disadvantages
- Hazards of dye toxicity
- more expensive
- must be confirmed by Z-N stain
DrTVRao MD 17
LowensteinndashJensen mediumbull When grown on LJ
medium M tuberculosis appears as brown granular colonies (sometimes called buff rough and tough) The media must be incubated for a significant length of time usually four weeks due to the slow doubling time of M tuberculosis DrTVRao MD 18
3- Cultures on L J media
Lowenstein ndashJensen medium is an egg based media
with addition of salts 5 glycerol Malachite green
Advantages - Specificity about 99
- More sensitive (need lower no of bacilli 10-100 ml)
- Can differentiate between TB complex amp NTM using biochemical reactions
- Sensitivity tests for antituberculous drugs
( St INH Rif E)
Disadvantages Slowly growing ( up to 8 weeks )DrTVRao MD 19
Recent Methods for Diagnosis
I ndashBACTEC 460 ( rapid radiometric culture system )specimens are cultured in a liquid medium
(Middle brook7H9 broth base )containing C14 ndashlabelled palmitic acid amp PANTA antibiotic mixture
Growing mycobacteria utilize the acid releasing radioactive CO2 which is measured as growth index (GI) in the BACTEC instrument
The daily increase in GI output is directly proportional to the rate amp amount of growth in the medium
Mycobacteria Growth Indicator
Tube (MGIT)
Tube contains modified Middlebrook 7H9
broth base with OADC enrichment amp
PANTA antibiotic mixture
All types of clinical specimens pulmonary
as well as extra-pulmonary ( except
blood) could be cultured on this type of
media
The MGIT 960 System
The MGIT 960 system is a non-radiometeric
automated system that uses the MGIT media amp
sensors to detect the fluorescence
Advantages
-The system holds 960 plastic tubes which are
continuously monitored
- Early detection as the machine monitoring amp
reading the tubes every hour
Detection and identification of mycobacteria directly
from clinical samplesbull Genotypic Methods
bull 1048708 PCR
bull 1048708 LAMP
bull 1048708 TMA NAA
bull 1048708 Ligase chain reaction
bull 1048708 Phenotypic Methods
bull 1048708 FAST Plaque TB
DrTVRao MD 23
bull Essentially PCR is a way to make millions of identical copies of a specific DNA sequence which may be a gene or a part of a gene or simply a stretch of nucleotides with a known DNA sequence the function of which may be unknown
Polymerase Chain Reaction (PCR)
DrTVRao MD 24
Polymerase Chain Reaction (PCR) amp
Gene probeNucleic acid probes amp nucleic acid amplification
tests in which polymerase enzymes are used to
amplify ( make many copies of specific DNA or
RNA sequences extracted from mycobacterial
cells
Advantages
- Rapid procedure - High sensitivity (1-10
( 3 ndash 4 hours) bacilli ml sputum)
bull Interferon-γ assays measure cell-mediated immunity by quantifying IFN-γ released from sensitized T cells in whole bloodPBMCs incubated with TB antigens
Quantiferon-GOLD
DrTVRao MD 26
What Positive Skin Test ( Tuberculin Test means)
bull A positive TB skin test or TB blood test only tells that a person has been infected with TB bacteria It does not tell whether the person has latent TB infection (LTBI) or has progressed to TB disease
DrTVRao MD 27
Tuberculin TestInterpretation A positive test indicates previous exposure and
carriage of TB A negative tuberculin test excludes infection in
suspected persons Tuberculin positive persons may develop
reactivation type of TB Tuberculin negative persons are at risk of gaining
new infection False positive reactions are mainly due to
- Infection with nontuberculous mycobacteria
DrTVRao MD 28
False negative reactions may be due to-
bull False negative reactions may be due to
- Sever tuberculosis infection (Miliary TB) -Hodgkinrsquos disease
bull Corticosteroid therapy - Malnutrition -AIDS
bull Children below 5 years of age with no exposure history
bull Positive test must be regarded suspicious
DrTVRao MD 29
Tuberculin Test( Mantoux Test )
bull Test to be interpreted in relation to clinical evaluation
bull Even the induration of 5 mm to be considered positive when tested on HIV patients
bull Lacks specificity
Positive Test Means
bull This means the personrsquos body was infected with TB bacteria Additional tests are needed to determine if the person has latent TB infection or TB disease A health care worker will then provide treatment as needed
DrTVRao MD 31
Negative Test Means
bull This means the personrsquos body did not react to the test and that latent TB infection or TB disease is not likely
DrTVRao MD 32
Tuberculin Testing - Limitations
bull False positive reactions are mainly due to
bull - Infection with nontuberculous mycobacteria
bull False negative reactions may be due to
bull - Sever tuberculosis infection (Miliary TB) -Hodgkinrsquos disease
bull - Corticosteroid therapy - Malnutrition -AIDS
bull Children below 5 years of age with no exposure history
bull - Positive test must be regarded suspicious DrTVRao MD 33
Recent Methods for Diagnosis
I ndash BACTEC 460 ( rapid radiometric culture system )
Specimens are cultured in a liquid medium (Middle brook7H9 broth base )containing C14 ndash labeled palmitic acid amp PANTA antibiotic mixture
Growing mycobacteria utilize the acid releasing radioactive CO2 which is measured as growth index (GI) in the BACTEC instrument
The daily increase in GI output is directly proportional to the rate amp amount of growth in the medium
DrTVRao MD 34
TB blood testsbull TB blood tests (also called interferon-gamma
release assays or IGRAs) measure how the immune system reacts to the bacteria that cause TB An IGRA measures how strong a personrsquos immune system reacts to TB bacteria by testing the personrsquos blood in a laboratory
bull Two IGRAs are approved by the US Food and Drug Administration (FDA) and are available in the United States
DrTVRao MD 35
Positive IGRAbull This means that the
person has been infected with TB bacteria Additional tests are needed to determine if the person has latent TB infection or TB disease A health care worker will then provide treatment as needed
DrTVRao MD 36
Negative IGRA
bull This means that the personrsquos blood did not react to the test and that latent TB infection or TB disease is not likely
DrTVRao MD 37
IGRAs are the preferred method of TB infection testing for the following
People who have received bacilli ChalmettendashGueacuterin (BCG) BCG is a vaccine for TB disease People who have a difficult time returning for a second appointment to look for a reaction to the TST
There is no problem with repeated IGRAs
DrTVRao MD 38
III Polymerase Chain Reaction
(PCR) amp Gene probeNucleic acid probes amp nucleic acid amplification
tests in which polymerase enzymes are used to
amplify ( make many copies of specific DNA or
RNA sequences extracted from mycobacterial
cells
Advantages
- Rapid procedure - High sensitivity (1-10
( 3 ndash 4 hours) bacilli ml sputum)
DrTVRao MD 39
Molecular DR testing is particularly useful for
bull Patients suspected or at high risk of having drug-resistant TBvery ill patients for whom drug-susceptibility information might alter case management decisions such as patients who do not get better while taking standard first-line therapy
DrTVRao MD 40
Detection of MDR Tuberculosis
bull Very ill patients for whom drug-susceptibility information might alter case management decisions such as patients who do not get better while taking standard first-line therapy
DrTVRao MD 41
Detection of MDR Tuberculosis
bull outbreak or contact investigations when drug resistance is suspected in the source case or in some severely immunocompromised persons such as HIV-infected persons or those receiving dialysis in which knowledge of drug-susceptibility would be a significant benefit and affect preventive therapy decisions
DrTVRao MD 42
Tuberculosis and HIV infection
bull HIV association has become a threat to the developed countries too
bull HIV association will lead to rapid spread of tuberculosis
DrTVRao MD 43
HIV Considerations
bull HIV is the strongest risk factor for progression to active disease
bull HIV kills CD4+ T Helper cells which normally inhibit M tuberculosis
bull HIV interferes with PPD skin test
bull Protease inhibitors interfere with rifampin
DrTVRao MD 44
Epidemiologybull An ancient disease called as white plague
bull 13 of the world population is infected
bull 2 billion infected
bull Each year 9 lakhs to 1 million are infected
bull Poor nations phase the burnt of the disease
bull In developing world gt 4o of the population is effected
bull 15 million suffer the disease
bull 3 million are highly infective
DrTVRao MD 45
MDR tuberculosis
bull Multidrug resistant tuberculosis has become a global threat
bull In 1993 WHO declared Tuberculosis a Global emergency
bull Animals shed the bacilli in Milk humanrsquos get infected after drinking the unsterilized Milk
bull Pasteurization has reduced the incidence of Bovine tuberculosis
DrTVRao MD 46
Why Tuberculosis continues to be Important
bull Someone in the world is newly infected with TB bacilli every second
bull Overall one-third of the worlds population is currently infected with the TB bacillus
bull 5-10 of people who are infected with TB bacilli (but who are not infected with HIV) become sick or infectious at some time during their life People with HIV and TB infection are much more likely to develop TB
DrTVRao MD 47
bull Programme Created by DrTVRao MD for Medical and Paramedical
Students in Developing world
bull Email
bull doctortvraogmailcom
DrTVRao MD 48
![Page 11: Diagnosis of tuberculosis an Update](https://reader031.fdocuments.in/reader031/viewer/2022032113/55a62b711a28abd5138b48bb/html5/thumbnails/11.jpg)
Sputum Collectionbull Sputum specimens
are essential to confirm TBndash Specimens should be
from lung secretions not saliva
bull Collect 3 specimens on 3 different days
bull Spontaneous morning sputum more desirable than induced specimens
bull Collect sputum before treatment is initiated
11
Interpretation of sputum stained by
Z N Stain (WHO )
More than 10 bacilli field ------- +++
From 1 ndash 10 bacilli field ------- ++
From 10 ndash 99 bacilli 100 fields ----- +
From 1 -9 bacilli100 fields ------ write the no
No bacilli seen ---------- negative
2- Detecting AFB by fluorochrome stain using fluorescence microscopy
The smear may be stained by auramine-O dye In this method the TB bacilli are stained yellow against dark background amp easily visualized using florescent microscope
Advantages
- More sensitive
- Rapid
Disadvantages
- Hazards of dye toxicity
- more expensive
- must be confirmed by Z-N stain
Acid Fast Bacilli under Fluorescent Microscope
DrTVRao MD 14
Culturebull Used to confirm
diagnosis of TB
bull Culture all
specimens even if
smear is negative
bull Initial drug isolate
should be used to
determine drug
susceptibility15
Laboratory Diagnosis
1- Sputum smears stained by Z-N stain
Three morning successive mucopurulent sputum samples are needed to diagnose pulmonary TB
Advantage - cheap ndash rapid
- Easy to perform
- High predictive value gt 90
- Specificity of 98
Disadvantages
- sputum ( need to contain 5000-10000 AFB ml)
- Young children elderly amp HIV infected persons may not produce cavities amp sputum containing AFB
DrTVRao MD 16
2- Detecting AFB by fluorochrome stain using fluorescence microscopy
The smear may be stained by aura mine-O dye In this method the TB bacilli are stained yellow against dark background amp easily visualized using florescent microscope
Advantages
- More sensitive
- Rapid
Disadvantages
- Hazards of dye toxicity
- more expensive
- must be confirmed by Z-N stain
DrTVRao MD 17
LowensteinndashJensen mediumbull When grown on LJ
medium M tuberculosis appears as brown granular colonies (sometimes called buff rough and tough) The media must be incubated for a significant length of time usually four weeks due to the slow doubling time of M tuberculosis DrTVRao MD 18
3- Cultures on L J media
Lowenstein ndashJensen medium is an egg based media
with addition of salts 5 glycerol Malachite green
Advantages - Specificity about 99
- More sensitive (need lower no of bacilli 10-100 ml)
- Can differentiate between TB complex amp NTM using biochemical reactions
- Sensitivity tests for antituberculous drugs
( St INH Rif E)
Disadvantages Slowly growing ( up to 8 weeks )DrTVRao MD 19
Recent Methods for Diagnosis
I ndashBACTEC 460 ( rapid radiometric culture system )specimens are cultured in a liquid medium
(Middle brook7H9 broth base )containing C14 ndashlabelled palmitic acid amp PANTA antibiotic mixture
Growing mycobacteria utilize the acid releasing radioactive CO2 which is measured as growth index (GI) in the BACTEC instrument
The daily increase in GI output is directly proportional to the rate amp amount of growth in the medium
Mycobacteria Growth Indicator
Tube (MGIT)
Tube contains modified Middlebrook 7H9
broth base with OADC enrichment amp
PANTA antibiotic mixture
All types of clinical specimens pulmonary
as well as extra-pulmonary ( except
blood) could be cultured on this type of
media
The MGIT 960 System
The MGIT 960 system is a non-radiometeric
automated system that uses the MGIT media amp
sensors to detect the fluorescence
Advantages
-The system holds 960 plastic tubes which are
continuously monitored
- Early detection as the machine monitoring amp
reading the tubes every hour
Detection and identification of mycobacteria directly
from clinical samplesbull Genotypic Methods
bull 1048708 PCR
bull 1048708 LAMP
bull 1048708 TMA NAA
bull 1048708 Ligase chain reaction
bull 1048708 Phenotypic Methods
bull 1048708 FAST Plaque TB
DrTVRao MD 23
bull Essentially PCR is a way to make millions of identical copies of a specific DNA sequence which may be a gene or a part of a gene or simply a stretch of nucleotides with a known DNA sequence the function of which may be unknown
Polymerase Chain Reaction (PCR)
DrTVRao MD 24
Polymerase Chain Reaction (PCR) amp
Gene probeNucleic acid probes amp nucleic acid amplification
tests in which polymerase enzymes are used to
amplify ( make many copies of specific DNA or
RNA sequences extracted from mycobacterial
cells
Advantages
- Rapid procedure - High sensitivity (1-10
( 3 ndash 4 hours) bacilli ml sputum)
bull Interferon-γ assays measure cell-mediated immunity by quantifying IFN-γ released from sensitized T cells in whole bloodPBMCs incubated with TB antigens
Quantiferon-GOLD
DrTVRao MD 26
What Positive Skin Test ( Tuberculin Test means)
bull A positive TB skin test or TB blood test only tells that a person has been infected with TB bacteria It does not tell whether the person has latent TB infection (LTBI) or has progressed to TB disease
DrTVRao MD 27
Tuberculin TestInterpretation A positive test indicates previous exposure and
carriage of TB A negative tuberculin test excludes infection in
suspected persons Tuberculin positive persons may develop
reactivation type of TB Tuberculin negative persons are at risk of gaining
new infection False positive reactions are mainly due to
- Infection with nontuberculous mycobacteria
DrTVRao MD 28
False negative reactions may be due to-
bull False negative reactions may be due to
- Sever tuberculosis infection (Miliary TB) -Hodgkinrsquos disease
bull Corticosteroid therapy - Malnutrition -AIDS
bull Children below 5 years of age with no exposure history
bull Positive test must be regarded suspicious
DrTVRao MD 29
Tuberculin Test( Mantoux Test )
bull Test to be interpreted in relation to clinical evaluation
bull Even the induration of 5 mm to be considered positive when tested on HIV patients
bull Lacks specificity
Positive Test Means
bull This means the personrsquos body was infected with TB bacteria Additional tests are needed to determine if the person has latent TB infection or TB disease A health care worker will then provide treatment as needed
DrTVRao MD 31
Negative Test Means
bull This means the personrsquos body did not react to the test and that latent TB infection or TB disease is not likely
DrTVRao MD 32
Tuberculin Testing - Limitations
bull False positive reactions are mainly due to
bull - Infection with nontuberculous mycobacteria
bull False negative reactions may be due to
bull - Sever tuberculosis infection (Miliary TB) -Hodgkinrsquos disease
bull - Corticosteroid therapy - Malnutrition -AIDS
bull Children below 5 years of age with no exposure history
bull - Positive test must be regarded suspicious DrTVRao MD 33
Recent Methods for Diagnosis
I ndash BACTEC 460 ( rapid radiometric culture system )
Specimens are cultured in a liquid medium (Middle brook7H9 broth base )containing C14 ndash labeled palmitic acid amp PANTA antibiotic mixture
Growing mycobacteria utilize the acid releasing radioactive CO2 which is measured as growth index (GI) in the BACTEC instrument
The daily increase in GI output is directly proportional to the rate amp amount of growth in the medium
DrTVRao MD 34
TB blood testsbull TB blood tests (also called interferon-gamma
release assays or IGRAs) measure how the immune system reacts to the bacteria that cause TB An IGRA measures how strong a personrsquos immune system reacts to TB bacteria by testing the personrsquos blood in a laboratory
bull Two IGRAs are approved by the US Food and Drug Administration (FDA) and are available in the United States
DrTVRao MD 35
Positive IGRAbull This means that the
person has been infected with TB bacteria Additional tests are needed to determine if the person has latent TB infection or TB disease A health care worker will then provide treatment as needed
DrTVRao MD 36
Negative IGRA
bull This means that the personrsquos blood did not react to the test and that latent TB infection or TB disease is not likely
DrTVRao MD 37
IGRAs are the preferred method of TB infection testing for the following
People who have received bacilli ChalmettendashGueacuterin (BCG) BCG is a vaccine for TB disease People who have a difficult time returning for a second appointment to look for a reaction to the TST
There is no problem with repeated IGRAs
DrTVRao MD 38
III Polymerase Chain Reaction
(PCR) amp Gene probeNucleic acid probes amp nucleic acid amplification
tests in which polymerase enzymes are used to
amplify ( make many copies of specific DNA or
RNA sequences extracted from mycobacterial
cells
Advantages
- Rapid procedure - High sensitivity (1-10
( 3 ndash 4 hours) bacilli ml sputum)
DrTVRao MD 39
Molecular DR testing is particularly useful for
bull Patients suspected or at high risk of having drug-resistant TBvery ill patients for whom drug-susceptibility information might alter case management decisions such as patients who do not get better while taking standard first-line therapy
DrTVRao MD 40
Detection of MDR Tuberculosis
bull Very ill patients for whom drug-susceptibility information might alter case management decisions such as patients who do not get better while taking standard first-line therapy
DrTVRao MD 41
Detection of MDR Tuberculosis
bull outbreak or contact investigations when drug resistance is suspected in the source case or in some severely immunocompromised persons such as HIV-infected persons or those receiving dialysis in which knowledge of drug-susceptibility would be a significant benefit and affect preventive therapy decisions
DrTVRao MD 42
Tuberculosis and HIV infection
bull HIV association has become a threat to the developed countries too
bull HIV association will lead to rapid spread of tuberculosis
DrTVRao MD 43
HIV Considerations
bull HIV is the strongest risk factor for progression to active disease
bull HIV kills CD4+ T Helper cells which normally inhibit M tuberculosis
bull HIV interferes with PPD skin test
bull Protease inhibitors interfere with rifampin
DrTVRao MD 44
Epidemiologybull An ancient disease called as white plague
bull 13 of the world population is infected
bull 2 billion infected
bull Each year 9 lakhs to 1 million are infected
bull Poor nations phase the burnt of the disease
bull In developing world gt 4o of the population is effected
bull 15 million suffer the disease
bull 3 million are highly infective
DrTVRao MD 45
MDR tuberculosis
bull Multidrug resistant tuberculosis has become a global threat
bull In 1993 WHO declared Tuberculosis a Global emergency
bull Animals shed the bacilli in Milk humanrsquos get infected after drinking the unsterilized Milk
bull Pasteurization has reduced the incidence of Bovine tuberculosis
DrTVRao MD 46
Why Tuberculosis continues to be Important
bull Someone in the world is newly infected with TB bacilli every second
bull Overall one-third of the worlds population is currently infected with the TB bacillus
bull 5-10 of people who are infected with TB bacilli (but who are not infected with HIV) become sick or infectious at some time during their life People with HIV and TB infection are much more likely to develop TB
DrTVRao MD 47
bull Programme Created by DrTVRao MD for Medical and Paramedical
Students in Developing world
bull Email
bull doctortvraogmailcom
DrTVRao MD 48
![Page 12: Diagnosis of tuberculosis an Update](https://reader031.fdocuments.in/reader031/viewer/2022032113/55a62b711a28abd5138b48bb/html5/thumbnails/12.jpg)
Interpretation of sputum stained by
Z N Stain (WHO )
More than 10 bacilli field ------- +++
From 1 ndash 10 bacilli field ------- ++
From 10 ndash 99 bacilli 100 fields ----- +
From 1 -9 bacilli100 fields ------ write the no
No bacilli seen ---------- negative
2- Detecting AFB by fluorochrome stain using fluorescence microscopy
The smear may be stained by auramine-O dye In this method the TB bacilli are stained yellow against dark background amp easily visualized using florescent microscope
Advantages
- More sensitive
- Rapid
Disadvantages
- Hazards of dye toxicity
- more expensive
- must be confirmed by Z-N stain
Acid Fast Bacilli under Fluorescent Microscope
DrTVRao MD 14
Culturebull Used to confirm
diagnosis of TB
bull Culture all
specimens even if
smear is negative
bull Initial drug isolate
should be used to
determine drug
susceptibility15
Laboratory Diagnosis
1- Sputum smears stained by Z-N stain
Three morning successive mucopurulent sputum samples are needed to diagnose pulmonary TB
Advantage - cheap ndash rapid
- Easy to perform
- High predictive value gt 90
- Specificity of 98
Disadvantages
- sputum ( need to contain 5000-10000 AFB ml)
- Young children elderly amp HIV infected persons may not produce cavities amp sputum containing AFB
DrTVRao MD 16
2- Detecting AFB by fluorochrome stain using fluorescence microscopy
The smear may be stained by aura mine-O dye In this method the TB bacilli are stained yellow against dark background amp easily visualized using florescent microscope
Advantages
- More sensitive
- Rapid
Disadvantages
- Hazards of dye toxicity
- more expensive
- must be confirmed by Z-N stain
DrTVRao MD 17
LowensteinndashJensen mediumbull When grown on LJ
medium M tuberculosis appears as brown granular colonies (sometimes called buff rough and tough) The media must be incubated for a significant length of time usually four weeks due to the slow doubling time of M tuberculosis DrTVRao MD 18
3- Cultures on L J media
Lowenstein ndashJensen medium is an egg based media
with addition of salts 5 glycerol Malachite green
Advantages - Specificity about 99
- More sensitive (need lower no of bacilli 10-100 ml)
- Can differentiate between TB complex amp NTM using biochemical reactions
- Sensitivity tests for antituberculous drugs
( St INH Rif E)
Disadvantages Slowly growing ( up to 8 weeks )DrTVRao MD 19
Recent Methods for Diagnosis
I ndashBACTEC 460 ( rapid radiometric culture system )specimens are cultured in a liquid medium
(Middle brook7H9 broth base )containing C14 ndashlabelled palmitic acid amp PANTA antibiotic mixture
Growing mycobacteria utilize the acid releasing radioactive CO2 which is measured as growth index (GI) in the BACTEC instrument
The daily increase in GI output is directly proportional to the rate amp amount of growth in the medium
Mycobacteria Growth Indicator
Tube (MGIT)
Tube contains modified Middlebrook 7H9
broth base with OADC enrichment amp
PANTA antibiotic mixture
All types of clinical specimens pulmonary
as well as extra-pulmonary ( except
blood) could be cultured on this type of
media
The MGIT 960 System
The MGIT 960 system is a non-radiometeric
automated system that uses the MGIT media amp
sensors to detect the fluorescence
Advantages
-The system holds 960 plastic tubes which are
continuously monitored
- Early detection as the machine monitoring amp
reading the tubes every hour
Detection and identification of mycobacteria directly
from clinical samplesbull Genotypic Methods
bull 1048708 PCR
bull 1048708 LAMP
bull 1048708 TMA NAA
bull 1048708 Ligase chain reaction
bull 1048708 Phenotypic Methods
bull 1048708 FAST Plaque TB
DrTVRao MD 23
bull Essentially PCR is a way to make millions of identical copies of a specific DNA sequence which may be a gene or a part of a gene or simply a stretch of nucleotides with a known DNA sequence the function of which may be unknown
Polymerase Chain Reaction (PCR)
DrTVRao MD 24
Polymerase Chain Reaction (PCR) amp
Gene probeNucleic acid probes amp nucleic acid amplification
tests in which polymerase enzymes are used to
amplify ( make many copies of specific DNA or
RNA sequences extracted from mycobacterial
cells
Advantages
- Rapid procedure - High sensitivity (1-10
( 3 ndash 4 hours) bacilli ml sputum)
bull Interferon-γ assays measure cell-mediated immunity by quantifying IFN-γ released from sensitized T cells in whole bloodPBMCs incubated with TB antigens
Quantiferon-GOLD
DrTVRao MD 26
What Positive Skin Test ( Tuberculin Test means)
bull A positive TB skin test or TB blood test only tells that a person has been infected with TB bacteria It does not tell whether the person has latent TB infection (LTBI) or has progressed to TB disease
DrTVRao MD 27
Tuberculin TestInterpretation A positive test indicates previous exposure and
carriage of TB A negative tuberculin test excludes infection in
suspected persons Tuberculin positive persons may develop
reactivation type of TB Tuberculin negative persons are at risk of gaining
new infection False positive reactions are mainly due to
- Infection with nontuberculous mycobacteria
DrTVRao MD 28
False negative reactions may be due to-
bull False negative reactions may be due to
- Sever tuberculosis infection (Miliary TB) -Hodgkinrsquos disease
bull Corticosteroid therapy - Malnutrition -AIDS
bull Children below 5 years of age with no exposure history
bull Positive test must be regarded suspicious
DrTVRao MD 29
Tuberculin Test( Mantoux Test )
bull Test to be interpreted in relation to clinical evaluation
bull Even the induration of 5 mm to be considered positive when tested on HIV patients
bull Lacks specificity
Positive Test Means
bull This means the personrsquos body was infected with TB bacteria Additional tests are needed to determine if the person has latent TB infection or TB disease A health care worker will then provide treatment as needed
DrTVRao MD 31
Negative Test Means
bull This means the personrsquos body did not react to the test and that latent TB infection or TB disease is not likely
DrTVRao MD 32
Tuberculin Testing - Limitations
bull False positive reactions are mainly due to
bull - Infection with nontuberculous mycobacteria
bull False negative reactions may be due to
bull - Sever tuberculosis infection (Miliary TB) -Hodgkinrsquos disease
bull - Corticosteroid therapy - Malnutrition -AIDS
bull Children below 5 years of age with no exposure history
bull - Positive test must be regarded suspicious DrTVRao MD 33
Recent Methods for Diagnosis
I ndash BACTEC 460 ( rapid radiometric culture system )
Specimens are cultured in a liquid medium (Middle brook7H9 broth base )containing C14 ndash labeled palmitic acid amp PANTA antibiotic mixture
Growing mycobacteria utilize the acid releasing radioactive CO2 which is measured as growth index (GI) in the BACTEC instrument
The daily increase in GI output is directly proportional to the rate amp amount of growth in the medium
DrTVRao MD 34
TB blood testsbull TB blood tests (also called interferon-gamma
release assays or IGRAs) measure how the immune system reacts to the bacteria that cause TB An IGRA measures how strong a personrsquos immune system reacts to TB bacteria by testing the personrsquos blood in a laboratory
bull Two IGRAs are approved by the US Food and Drug Administration (FDA) and are available in the United States
DrTVRao MD 35
Positive IGRAbull This means that the
person has been infected with TB bacteria Additional tests are needed to determine if the person has latent TB infection or TB disease A health care worker will then provide treatment as needed
DrTVRao MD 36
Negative IGRA
bull This means that the personrsquos blood did not react to the test and that latent TB infection or TB disease is not likely
DrTVRao MD 37
IGRAs are the preferred method of TB infection testing for the following
People who have received bacilli ChalmettendashGueacuterin (BCG) BCG is a vaccine for TB disease People who have a difficult time returning for a second appointment to look for a reaction to the TST
There is no problem with repeated IGRAs
DrTVRao MD 38
III Polymerase Chain Reaction
(PCR) amp Gene probeNucleic acid probes amp nucleic acid amplification
tests in which polymerase enzymes are used to
amplify ( make many copies of specific DNA or
RNA sequences extracted from mycobacterial
cells
Advantages
- Rapid procedure - High sensitivity (1-10
( 3 ndash 4 hours) bacilli ml sputum)
DrTVRao MD 39
Molecular DR testing is particularly useful for
bull Patients suspected or at high risk of having drug-resistant TBvery ill patients for whom drug-susceptibility information might alter case management decisions such as patients who do not get better while taking standard first-line therapy
DrTVRao MD 40
Detection of MDR Tuberculosis
bull Very ill patients for whom drug-susceptibility information might alter case management decisions such as patients who do not get better while taking standard first-line therapy
DrTVRao MD 41
Detection of MDR Tuberculosis
bull outbreak or contact investigations when drug resistance is suspected in the source case or in some severely immunocompromised persons such as HIV-infected persons or those receiving dialysis in which knowledge of drug-susceptibility would be a significant benefit and affect preventive therapy decisions
DrTVRao MD 42
Tuberculosis and HIV infection
bull HIV association has become a threat to the developed countries too
bull HIV association will lead to rapid spread of tuberculosis
DrTVRao MD 43
HIV Considerations
bull HIV is the strongest risk factor for progression to active disease
bull HIV kills CD4+ T Helper cells which normally inhibit M tuberculosis
bull HIV interferes with PPD skin test
bull Protease inhibitors interfere with rifampin
DrTVRao MD 44
Epidemiologybull An ancient disease called as white plague
bull 13 of the world population is infected
bull 2 billion infected
bull Each year 9 lakhs to 1 million are infected
bull Poor nations phase the burnt of the disease
bull In developing world gt 4o of the population is effected
bull 15 million suffer the disease
bull 3 million are highly infective
DrTVRao MD 45
MDR tuberculosis
bull Multidrug resistant tuberculosis has become a global threat
bull In 1993 WHO declared Tuberculosis a Global emergency
bull Animals shed the bacilli in Milk humanrsquos get infected after drinking the unsterilized Milk
bull Pasteurization has reduced the incidence of Bovine tuberculosis
DrTVRao MD 46
Why Tuberculosis continues to be Important
bull Someone in the world is newly infected with TB bacilli every second
bull Overall one-third of the worlds population is currently infected with the TB bacillus
bull 5-10 of people who are infected with TB bacilli (but who are not infected with HIV) become sick or infectious at some time during their life People with HIV and TB infection are much more likely to develop TB
DrTVRao MD 47
bull Programme Created by DrTVRao MD for Medical and Paramedical
Students in Developing world
bull Email
bull doctortvraogmailcom
DrTVRao MD 48
![Page 13: Diagnosis of tuberculosis an Update](https://reader031.fdocuments.in/reader031/viewer/2022032113/55a62b711a28abd5138b48bb/html5/thumbnails/13.jpg)
2- Detecting AFB by fluorochrome stain using fluorescence microscopy
The smear may be stained by auramine-O dye In this method the TB bacilli are stained yellow against dark background amp easily visualized using florescent microscope
Advantages
- More sensitive
- Rapid
Disadvantages
- Hazards of dye toxicity
- more expensive
- must be confirmed by Z-N stain
Acid Fast Bacilli under Fluorescent Microscope
DrTVRao MD 14
Culturebull Used to confirm
diagnosis of TB
bull Culture all
specimens even if
smear is negative
bull Initial drug isolate
should be used to
determine drug
susceptibility15
Laboratory Diagnosis
1- Sputum smears stained by Z-N stain
Three morning successive mucopurulent sputum samples are needed to diagnose pulmonary TB
Advantage - cheap ndash rapid
- Easy to perform
- High predictive value gt 90
- Specificity of 98
Disadvantages
- sputum ( need to contain 5000-10000 AFB ml)
- Young children elderly amp HIV infected persons may not produce cavities amp sputum containing AFB
DrTVRao MD 16
2- Detecting AFB by fluorochrome stain using fluorescence microscopy
The smear may be stained by aura mine-O dye In this method the TB bacilli are stained yellow against dark background amp easily visualized using florescent microscope
Advantages
- More sensitive
- Rapid
Disadvantages
- Hazards of dye toxicity
- more expensive
- must be confirmed by Z-N stain
DrTVRao MD 17
LowensteinndashJensen mediumbull When grown on LJ
medium M tuberculosis appears as brown granular colonies (sometimes called buff rough and tough) The media must be incubated for a significant length of time usually four weeks due to the slow doubling time of M tuberculosis DrTVRao MD 18
3- Cultures on L J media
Lowenstein ndashJensen medium is an egg based media
with addition of salts 5 glycerol Malachite green
Advantages - Specificity about 99
- More sensitive (need lower no of bacilli 10-100 ml)
- Can differentiate between TB complex amp NTM using biochemical reactions
- Sensitivity tests for antituberculous drugs
( St INH Rif E)
Disadvantages Slowly growing ( up to 8 weeks )DrTVRao MD 19
Recent Methods for Diagnosis
I ndashBACTEC 460 ( rapid radiometric culture system )specimens are cultured in a liquid medium
(Middle brook7H9 broth base )containing C14 ndashlabelled palmitic acid amp PANTA antibiotic mixture
Growing mycobacteria utilize the acid releasing radioactive CO2 which is measured as growth index (GI) in the BACTEC instrument
The daily increase in GI output is directly proportional to the rate amp amount of growth in the medium
Mycobacteria Growth Indicator
Tube (MGIT)
Tube contains modified Middlebrook 7H9
broth base with OADC enrichment amp
PANTA antibiotic mixture
All types of clinical specimens pulmonary
as well as extra-pulmonary ( except
blood) could be cultured on this type of
media
The MGIT 960 System
The MGIT 960 system is a non-radiometeric
automated system that uses the MGIT media amp
sensors to detect the fluorescence
Advantages
-The system holds 960 plastic tubes which are
continuously monitored
- Early detection as the machine monitoring amp
reading the tubes every hour
Detection and identification of mycobacteria directly
from clinical samplesbull Genotypic Methods
bull 1048708 PCR
bull 1048708 LAMP
bull 1048708 TMA NAA
bull 1048708 Ligase chain reaction
bull 1048708 Phenotypic Methods
bull 1048708 FAST Plaque TB
DrTVRao MD 23
bull Essentially PCR is a way to make millions of identical copies of a specific DNA sequence which may be a gene or a part of a gene or simply a stretch of nucleotides with a known DNA sequence the function of which may be unknown
Polymerase Chain Reaction (PCR)
DrTVRao MD 24
Polymerase Chain Reaction (PCR) amp
Gene probeNucleic acid probes amp nucleic acid amplification
tests in which polymerase enzymes are used to
amplify ( make many copies of specific DNA or
RNA sequences extracted from mycobacterial
cells
Advantages
- Rapid procedure - High sensitivity (1-10
( 3 ndash 4 hours) bacilli ml sputum)
bull Interferon-γ assays measure cell-mediated immunity by quantifying IFN-γ released from sensitized T cells in whole bloodPBMCs incubated with TB antigens
Quantiferon-GOLD
DrTVRao MD 26
What Positive Skin Test ( Tuberculin Test means)
bull A positive TB skin test or TB blood test only tells that a person has been infected with TB bacteria It does not tell whether the person has latent TB infection (LTBI) or has progressed to TB disease
DrTVRao MD 27
Tuberculin TestInterpretation A positive test indicates previous exposure and
carriage of TB A negative tuberculin test excludes infection in
suspected persons Tuberculin positive persons may develop
reactivation type of TB Tuberculin negative persons are at risk of gaining
new infection False positive reactions are mainly due to
- Infection with nontuberculous mycobacteria
DrTVRao MD 28
False negative reactions may be due to-
bull False negative reactions may be due to
- Sever tuberculosis infection (Miliary TB) -Hodgkinrsquos disease
bull Corticosteroid therapy - Malnutrition -AIDS
bull Children below 5 years of age with no exposure history
bull Positive test must be regarded suspicious
DrTVRao MD 29
Tuberculin Test( Mantoux Test )
bull Test to be interpreted in relation to clinical evaluation
bull Even the induration of 5 mm to be considered positive when tested on HIV patients
bull Lacks specificity
Positive Test Means
bull This means the personrsquos body was infected with TB bacteria Additional tests are needed to determine if the person has latent TB infection or TB disease A health care worker will then provide treatment as needed
DrTVRao MD 31
Negative Test Means
bull This means the personrsquos body did not react to the test and that latent TB infection or TB disease is not likely
DrTVRao MD 32
Tuberculin Testing - Limitations
bull False positive reactions are mainly due to
bull - Infection with nontuberculous mycobacteria
bull False negative reactions may be due to
bull - Sever tuberculosis infection (Miliary TB) -Hodgkinrsquos disease
bull - Corticosteroid therapy - Malnutrition -AIDS
bull Children below 5 years of age with no exposure history
bull - Positive test must be regarded suspicious DrTVRao MD 33
Recent Methods for Diagnosis
I ndash BACTEC 460 ( rapid radiometric culture system )
Specimens are cultured in a liquid medium (Middle brook7H9 broth base )containing C14 ndash labeled palmitic acid amp PANTA antibiotic mixture
Growing mycobacteria utilize the acid releasing radioactive CO2 which is measured as growth index (GI) in the BACTEC instrument
The daily increase in GI output is directly proportional to the rate amp amount of growth in the medium
DrTVRao MD 34
TB blood testsbull TB blood tests (also called interferon-gamma
release assays or IGRAs) measure how the immune system reacts to the bacteria that cause TB An IGRA measures how strong a personrsquos immune system reacts to TB bacteria by testing the personrsquos blood in a laboratory
bull Two IGRAs are approved by the US Food and Drug Administration (FDA) and are available in the United States
DrTVRao MD 35
Positive IGRAbull This means that the
person has been infected with TB bacteria Additional tests are needed to determine if the person has latent TB infection or TB disease A health care worker will then provide treatment as needed
DrTVRao MD 36
Negative IGRA
bull This means that the personrsquos blood did not react to the test and that latent TB infection or TB disease is not likely
DrTVRao MD 37
IGRAs are the preferred method of TB infection testing for the following
People who have received bacilli ChalmettendashGueacuterin (BCG) BCG is a vaccine for TB disease People who have a difficult time returning for a second appointment to look for a reaction to the TST
There is no problem with repeated IGRAs
DrTVRao MD 38
III Polymerase Chain Reaction
(PCR) amp Gene probeNucleic acid probes amp nucleic acid amplification
tests in which polymerase enzymes are used to
amplify ( make many copies of specific DNA or
RNA sequences extracted from mycobacterial
cells
Advantages
- Rapid procedure - High sensitivity (1-10
( 3 ndash 4 hours) bacilli ml sputum)
DrTVRao MD 39
Molecular DR testing is particularly useful for
bull Patients suspected or at high risk of having drug-resistant TBvery ill patients for whom drug-susceptibility information might alter case management decisions such as patients who do not get better while taking standard first-line therapy
DrTVRao MD 40
Detection of MDR Tuberculosis
bull Very ill patients for whom drug-susceptibility information might alter case management decisions such as patients who do not get better while taking standard first-line therapy
DrTVRao MD 41
Detection of MDR Tuberculosis
bull outbreak or contact investigations when drug resistance is suspected in the source case or in some severely immunocompromised persons such as HIV-infected persons or those receiving dialysis in which knowledge of drug-susceptibility would be a significant benefit and affect preventive therapy decisions
DrTVRao MD 42
Tuberculosis and HIV infection
bull HIV association has become a threat to the developed countries too
bull HIV association will lead to rapid spread of tuberculosis
DrTVRao MD 43
HIV Considerations
bull HIV is the strongest risk factor for progression to active disease
bull HIV kills CD4+ T Helper cells which normally inhibit M tuberculosis
bull HIV interferes with PPD skin test
bull Protease inhibitors interfere with rifampin
DrTVRao MD 44
Epidemiologybull An ancient disease called as white plague
bull 13 of the world population is infected
bull 2 billion infected
bull Each year 9 lakhs to 1 million are infected
bull Poor nations phase the burnt of the disease
bull In developing world gt 4o of the population is effected
bull 15 million suffer the disease
bull 3 million are highly infective
DrTVRao MD 45
MDR tuberculosis
bull Multidrug resistant tuberculosis has become a global threat
bull In 1993 WHO declared Tuberculosis a Global emergency
bull Animals shed the bacilli in Milk humanrsquos get infected after drinking the unsterilized Milk
bull Pasteurization has reduced the incidence of Bovine tuberculosis
DrTVRao MD 46
Why Tuberculosis continues to be Important
bull Someone in the world is newly infected with TB bacilli every second
bull Overall one-third of the worlds population is currently infected with the TB bacillus
bull 5-10 of people who are infected with TB bacilli (but who are not infected with HIV) become sick or infectious at some time during their life People with HIV and TB infection are much more likely to develop TB
DrTVRao MD 47
bull Programme Created by DrTVRao MD for Medical and Paramedical
Students in Developing world
bull Email
bull doctortvraogmailcom
DrTVRao MD 48
![Page 14: Diagnosis of tuberculosis an Update](https://reader031.fdocuments.in/reader031/viewer/2022032113/55a62b711a28abd5138b48bb/html5/thumbnails/14.jpg)
Acid Fast Bacilli under Fluorescent Microscope
DrTVRao MD 14
Culturebull Used to confirm
diagnosis of TB
bull Culture all
specimens even if
smear is negative
bull Initial drug isolate
should be used to
determine drug
susceptibility15
Laboratory Diagnosis
1- Sputum smears stained by Z-N stain
Three morning successive mucopurulent sputum samples are needed to diagnose pulmonary TB
Advantage - cheap ndash rapid
- Easy to perform
- High predictive value gt 90
- Specificity of 98
Disadvantages
- sputum ( need to contain 5000-10000 AFB ml)
- Young children elderly amp HIV infected persons may not produce cavities amp sputum containing AFB
DrTVRao MD 16
2- Detecting AFB by fluorochrome stain using fluorescence microscopy
The smear may be stained by aura mine-O dye In this method the TB bacilli are stained yellow against dark background amp easily visualized using florescent microscope
Advantages
- More sensitive
- Rapid
Disadvantages
- Hazards of dye toxicity
- more expensive
- must be confirmed by Z-N stain
DrTVRao MD 17
LowensteinndashJensen mediumbull When grown on LJ
medium M tuberculosis appears as brown granular colonies (sometimes called buff rough and tough) The media must be incubated for a significant length of time usually four weeks due to the slow doubling time of M tuberculosis DrTVRao MD 18
3- Cultures on L J media
Lowenstein ndashJensen medium is an egg based media
with addition of salts 5 glycerol Malachite green
Advantages - Specificity about 99
- More sensitive (need lower no of bacilli 10-100 ml)
- Can differentiate between TB complex amp NTM using biochemical reactions
- Sensitivity tests for antituberculous drugs
( St INH Rif E)
Disadvantages Slowly growing ( up to 8 weeks )DrTVRao MD 19
Recent Methods for Diagnosis
I ndashBACTEC 460 ( rapid radiometric culture system )specimens are cultured in a liquid medium
(Middle brook7H9 broth base )containing C14 ndashlabelled palmitic acid amp PANTA antibiotic mixture
Growing mycobacteria utilize the acid releasing radioactive CO2 which is measured as growth index (GI) in the BACTEC instrument
The daily increase in GI output is directly proportional to the rate amp amount of growth in the medium
Mycobacteria Growth Indicator
Tube (MGIT)
Tube contains modified Middlebrook 7H9
broth base with OADC enrichment amp
PANTA antibiotic mixture
All types of clinical specimens pulmonary
as well as extra-pulmonary ( except
blood) could be cultured on this type of
media
The MGIT 960 System
The MGIT 960 system is a non-radiometeric
automated system that uses the MGIT media amp
sensors to detect the fluorescence
Advantages
-The system holds 960 plastic tubes which are
continuously monitored
- Early detection as the machine monitoring amp
reading the tubes every hour
Detection and identification of mycobacteria directly
from clinical samplesbull Genotypic Methods
bull 1048708 PCR
bull 1048708 LAMP
bull 1048708 TMA NAA
bull 1048708 Ligase chain reaction
bull 1048708 Phenotypic Methods
bull 1048708 FAST Plaque TB
DrTVRao MD 23
bull Essentially PCR is a way to make millions of identical copies of a specific DNA sequence which may be a gene or a part of a gene or simply a stretch of nucleotides with a known DNA sequence the function of which may be unknown
Polymerase Chain Reaction (PCR)
DrTVRao MD 24
Polymerase Chain Reaction (PCR) amp
Gene probeNucleic acid probes amp nucleic acid amplification
tests in which polymerase enzymes are used to
amplify ( make many copies of specific DNA or
RNA sequences extracted from mycobacterial
cells
Advantages
- Rapid procedure - High sensitivity (1-10
( 3 ndash 4 hours) bacilli ml sputum)
bull Interferon-γ assays measure cell-mediated immunity by quantifying IFN-γ released from sensitized T cells in whole bloodPBMCs incubated with TB antigens
Quantiferon-GOLD
DrTVRao MD 26
What Positive Skin Test ( Tuberculin Test means)
bull A positive TB skin test or TB blood test only tells that a person has been infected with TB bacteria It does not tell whether the person has latent TB infection (LTBI) or has progressed to TB disease
DrTVRao MD 27
Tuberculin TestInterpretation A positive test indicates previous exposure and
carriage of TB A negative tuberculin test excludes infection in
suspected persons Tuberculin positive persons may develop
reactivation type of TB Tuberculin negative persons are at risk of gaining
new infection False positive reactions are mainly due to
- Infection with nontuberculous mycobacteria
DrTVRao MD 28
False negative reactions may be due to-
bull False negative reactions may be due to
- Sever tuberculosis infection (Miliary TB) -Hodgkinrsquos disease
bull Corticosteroid therapy - Malnutrition -AIDS
bull Children below 5 years of age with no exposure history
bull Positive test must be regarded suspicious
DrTVRao MD 29
Tuberculin Test( Mantoux Test )
bull Test to be interpreted in relation to clinical evaluation
bull Even the induration of 5 mm to be considered positive when tested on HIV patients
bull Lacks specificity
Positive Test Means
bull This means the personrsquos body was infected with TB bacteria Additional tests are needed to determine if the person has latent TB infection or TB disease A health care worker will then provide treatment as needed
DrTVRao MD 31
Negative Test Means
bull This means the personrsquos body did not react to the test and that latent TB infection or TB disease is not likely
DrTVRao MD 32
Tuberculin Testing - Limitations
bull False positive reactions are mainly due to
bull - Infection with nontuberculous mycobacteria
bull False negative reactions may be due to
bull - Sever tuberculosis infection (Miliary TB) -Hodgkinrsquos disease
bull - Corticosteroid therapy - Malnutrition -AIDS
bull Children below 5 years of age with no exposure history
bull - Positive test must be regarded suspicious DrTVRao MD 33
Recent Methods for Diagnosis
I ndash BACTEC 460 ( rapid radiometric culture system )
Specimens are cultured in a liquid medium (Middle brook7H9 broth base )containing C14 ndash labeled palmitic acid amp PANTA antibiotic mixture
Growing mycobacteria utilize the acid releasing radioactive CO2 which is measured as growth index (GI) in the BACTEC instrument
The daily increase in GI output is directly proportional to the rate amp amount of growth in the medium
DrTVRao MD 34
TB blood testsbull TB blood tests (also called interferon-gamma
release assays or IGRAs) measure how the immune system reacts to the bacteria that cause TB An IGRA measures how strong a personrsquos immune system reacts to TB bacteria by testing the personrsquos blood in a laboratory
bull Two IGRAs are approved by the US Food and Drug Administration (FDA) and are available in the United States
DrTVRao MD 35
Positive IGRAbull This means that the
person has been infected with TB bacteria Additional tests are needed to determine if the person has latent TB infection or TB disease A health care worker will then provide treatment as needed
DrTVRao MD 36
Negative IGRA
bull This means that the personrsquos blood did not react to the test and that latent TB infection or TB disease is not likely
DrTVRao MD 37
IGRAs are the preferred method of TB infection testing for the following
People who have received bacilli ChalmettendashGueacuterin (BCG) BCG is a vaccine for TB disease People who have a difficult time returning for a second appointment to look for a reaction to the TST
There is no problem with repeated IGRAs
DrTVRao MD 38
III Polymerase Chain Reaction
(PCR) amp Gene probeNucleic acid probes amp nucleic acid amplification
tests in which polymerase enzymes are used to
amplify ( make many copies of specific DNA or
RNA sequences extracted from mycobacterial
cells
Advantages
- Rapid procedure - High sensitivity (1-10
( 3 ndash 4 hours) bacilli ml sputum)
DrTVRao MD 39
Molecular DR testing is particularly useful for
bull Patients suspected or at high risk of having drug-resistant TBvery ill patients for whom drug-susceptibility information might alter case management decisions such as patients who do not get better while taking standard first-line therapy
DrTVRao MD 40
Detection of MDR Tuberculosis
bull Very ill patients for whom drug-susceptibility information might alter case management decisions such as patients who do not get better while taking standard first-line therapy
DrTVRao MD 41
Detection of MDR Tuberculosis
bull outbreak or contact investigations when drug resistance is suspected in the source case or in some severely immunocompromised persons such as HIV-infected persons or those receiving dialysis in which knowledge of drug-susceptibility would be a significant benefit and affect preventive therapy decisions
DrTVRao MD 42
Tuberculosis and HIV infection
bull HIV association has become a threat to the developed countries too
bull HIV association will lead to rapid spread of tuberculosis
DrTVRao MD 43
HIV Considerations
bull HIV is the strongest risk factor for progression to active disease
bull HIV kills CD4+ T Helper cells which normally inhibit M tuberculosis
bull HIV interferes with PPD skin test
bull Protease inhibitors interfere with rifampin
DrTVRao MD 44
Epidemiologybull An ancient disease called as white plague
bull 13 of the world population is infected
bull 2 billion infected
bull Each year 9 lakhs to 1 million are infected
bull Poor nations phase the burnt of the disease
bull In developing world gt 4o of the population is effected
bull 15 million suffer the disease
bull 3 million are highly infective
DrTVRao MD 45
MDR tuberculosis
bull Multidrug resistant tuberculosis has become a global threat
bull In 1993 WHO declared Tuberculosis a Global emergency
bull Animals shed the bacilli in Milk humanrsquos get infected after drinking the unsterilized Milk
bull Pasteurization has reduced the incidence of Bovine tuberculosis
DrTVRao MD 46
Why Tuberculosis continues to be Important
bull Someone in the world is newly infected with TB bacilli every second
bull Overall one-third of the worlds population is currently infected with the TB bacillus
bull 5-10 of people who are infected with TB bacilli (but who are not infected with HIV) become sick or infectious at some time during their life People with HIV and TB infection are much more likely to develop TB
DrTVRao MD 47
bull Programme Created by DrTVRao MD for Medical and Paramedical
Students in Developing world
bull Email
bull doctortvraogmailcom
DrTVRao MD 48
![Page 15: Diagnosis of tuberculosis an Update](https://reader031.fdocuments.in/reader031/viewer/2022032113/55a62b711a28abd5138b48bb/html5/thumbnails/15.jpg)
Culturebull Used to confirm
diagnosis of TB
bull Culture all
specimens even if
smear is negative
bull Initial drug isolate
should be used to
determine drug
susceptibility15
Laboratory Diagnosis
1- Sputum smears stained by Z-N stain
Three morning successive mucopurulent sputum samples are needed to diagnose pulmonary TB
Advantage - cheap ndash rapid
- Easy to perform
- High predictive value gt 90
- Specificity of 98
Disadvantages
- sputum ( need to contain 5000-10000 AFB ml)
- Young children elderly amp HIV infected persons may not produce cavities amp sputum containing AFB
DrTVRao MD 16
2- Detecting AFB by fluorochrome stain using fluorescence microscopy
The smear may be stained by aura mine-O dye In this method the TB bacilli are stained yellow against dark background amp easily visualized using florescent microscope
Advantages
- More sensitive
- Rapid
Disadvantages
- Hazards of dye toxicity
- more expensive
- must be confirmed by Z-N stain
DrTVRao MD 17
LowensteinndashJensen mediumbull When grown on LJ
medium M tuberculosis appears as brown granular colonies (sometimes called buff rough and tough) The media must be incubated for a significant length of time usually four weeks due to the slow doubling time of M tuberculosis DrTVRao MD 18
3- Cultures on L J media
Lowenstein ndashJensen medium is an egg based media
with addition of salts 5 glycerol Malachite green
Advantages - Specificity about 99
- More sensitive (need lower no of bacilli 10-100 ml)
- Can differentiate between TB complex amp NTM using biochemical reactions
- Sensitivity tests for antituberculous drugs
( St INH Rif E)
Disadvantages Slowly growing ( up to 8 weeks )DrTVRao MD 19
Recent Methods for Diagnosis
I ndashBACTEC 460 ( rapid radiometric culture system )specimens are cultured in a liquid medium
(Middle brook7H9 broth base )containing C14 ndashlabelled palmitic acid amp PANTA antibiotic mixture
Growing mycobacteria utilize the acid releasing radioactive CO2 which is measured as growth index (GI) in the BACTEC instrument
The daily increase in GI output is directly proportional to the rate amp amount of growth in the medium
Mycobacteria Growth Indicator
Tube (MGIT)
Tube contains modified Middlebrook 7H9
broth base with OADC enrichment amp
PANTA antibiotic mixture
All types of clinical specimens pulmonary
as well as extra-pulmonary ( except
blood) could be cultured on this type of
media
The MGIT 960 System
The MGIT 960 system is a non-radiometeric
automated system that uses the MGIT media amp
sensors to detect the fluorescence
Advantages
-The system holds 960 plastic tubes which are
continuously monitored
- Early detection as the machine monitoring amp
reading the tubes every hour
Detection and identification of mycobacteria directly
from clinical samplesbull Genotypic Methods
bull 1048708 PCR
bull 1048708 LAMP
bull 1048708 TMA NAA
bull 1048708 Ligase chain reaction
bull 1048708 Phenotypic Methods
bull 1048708 FAST Plaque TB
DrTVRao MD 23
bull Essentially PCR is a way to make millions of identical copies of a specific DNA sequence which may be a gene or a part of a gene or simply a stretch of nucleotides with a known DNA sequence the function of which may be unknown
Polymerase Chain Reaction (PCR)
DrTVRao MD 24
Polymerase Chain Reaction (PCR) amp
Gene probeNucleic acid probes amp nucleic acid amplification
tests in which polymerase enzymes are used to
amplify ( make many copies of specific DNA or
RNA sequences extracted from mycobacterial
cells
Advantages
- Rapid procedure - High sensitivity (1-10
( 3 ndash 4 hours) bacilli ml sputum)
bull Interferon-γ assays measure cell-mediated immunity by quantifying IFN-γ released from sensitized T cells in whole bloodPBMCs incubated with TB antigens
Quantiferon-GOLD
DrTVRao MD 26
What Positive Skin Test ( Tuberculin Test means)
bull A positive TB skin test or TB blood test only tells that a person has been infected with TB bacteria It does not tell whether the person has latent TB infection (LTBI) or has progressed to TB disease
DrTVRao MD 27
Tuberculin TestInterpretation A positive test indicates previous exposure and
carriage of TB A negative tuberculin test excludes infection in
suspected persons Tuberculin positive persons may develop
reactivation type of TB Tuberculin negative persons are at risk of gaining
new infection False positive reactions are mainly due to
- Infection with nontuberculous mycobacteria
DrTVRao MD 28
False negative reactions may be due to-
bull False negative reactions may be due to
- Sever tuberculosis infection (Miliary TB) -Hodgkinrsquos disease
bull Corticosteroid therapy - Malnutrition -AIDS
bull Children below 5 years of age with no exposure history
bull Positive test must be regarded suspicious
DrTVRao MD 29
Tuberculin Test( Mantoux Test )
bull Test to be interpreted in relation to clinical evaluation
bull Even the induration of 5 mm to be considered positive when tested on HIV patients
bull Lacks specificity
Positive Test Means
bull This means the personrsquos body was infected with TB bacteria Additional tests are needed to determine if the person has latent TB infection or TB disease A health care worker will then provide treatment as needed
DrTVRao MD 31
Negative Test Means
bull This means the personrsquos body did not react to the test and that latent TB infection or TB disease is not likely
DrTVRao MD 32
Tuberculin Testing - Limitations
bull False positive reactions are mainly due to
bull - Infection with nontuberculous mycobacteria
bull False negative reactions may be due to
bull - Sever tuberculosis infection (Miliary TB) -Hodgkinrsquos disease
bull - Corticosteroid therapy - Malnutrition -AIDS
bull Children below 5 years of age with no exposure history
bull - Positive test must be regarded suspicious DrTVRao MD 33
Recent Methods for Diagnosis
I ndash BACTEC 460 ( rapid radiometric culture system )
Specimens are cultured in a liquid medium (Middle brook7H9 broth base )containing C14 ndash labeled palmitic acid amp PANTA antibiotic mixture
Growing mycobacteria utilize the acid releasing radioactive CO2 which is measured as growth index (GI) in the BACTEC instrument
The daily increase in GI output is directly proportional to the rate amp amount of growth in the medium
DrTVRao MD 34
TB blood testsbull TB blood tests (also called interferon-gamma
release assays or IGRAs) measure how the immune system reacts to the bacteria that cause TB An IGRA measures how strong a personrsquos immune system reacts to TB bacteria by testing the personrsquos blood in a laboratory
bull Two IGRAs are approved by the US Food and Drug Administration (FDA) and are available in the United States
DrTVRao MD 35
Positive IGRAbull This means that the
person has been infected with TB bacteria Additional tests are needed to determine if the person has latent TB infection or TB disease A health care worker will then provide treatment as needed
DrTVRao MD 36
Negative IGRA
bull This means that the personrsquos blood did not react to the test and that latent TB infection or TB disease is not likely
DrTVRao MD 37
IGRAs are the preferred method of TB infection testing for the following
People who have received bacilli ChalmettendashGueacuterin (BCG) BCG is a vaccine for TB disease People who have a difficult time returning for a second appointment to look for a reaction to the TST
There is no problem with repeated IGRAs
DrTVRao MD 38
III Polymerase Chain Reaction
(PCR) amp Gene probeNucleic acid probes amp nucleic acid amplification
tests in which polymerase enzymes are used to
amplify ( make many copies of specific DNA or
RNA sequences extracted from mycobacterial
cells
Advantages
- Rapid procedure - High sensitivity (1-10
( 3 ndash 4 hours) bacilli ml sputum)
DrTVRao MD 39
Molecular DR testing is particularly useful for
bull Patients suspected or at high risk of having drug-resistant TBvery ill patients for whom drug-susceptibility information might alter case management decisions such as patients who do not get better while taking standard first-line therapy
DrTVRao MD 40
Detection of MDR Tuberculosis
bull Very ill patients for whom drug-susceptibility information might alter case management decisions such as patients who do not get better while taking standard first-line therapy
DrTVRao MD 41
Detection of MDR Tuberculosis
bull outbreak or contact investigations when drug resistance is suspected in the source case or in some severely immunocompromised persons such as HIV-infected persons or those receiving dialysis in which knowledge of drug-susceptibility would be a significant benefit and affect preventive therapy decisions
DrTVRao MD 42
Tuberculosis and HIV infection
bull HIV association has become a threat to the developed countries too
bull HIV association will lead to rapid spread of tuberculosis
DrTVRao MD 43
HIV Considerations
bull HIV is the strongest risk factor for progression to active disease
bull HIV kills CD4+ T Helper cells which normally inhibit M tuberculosis
bull HIV interferes with PPD skin test
bull Protease inhibitors interfere with rifampin
DrTVRao MD 44
Epidemiologybull An ancient disease called as white plague
bull 13 of the world population is infected
bull 2 billion infected
bull Each year 9 lakhs to 1 million are infected
bull Poor nations phase the burnt of the disease
bull In developing world gt 4o of the population is effected
bull 15 million suffer the disease
bull 3 million are highly infective
DrTVRao MD 45
MDR tuberculosis
bull Multidrug resistant tuberculosis has become a global threat
bull In 1993 WHO declared Tuberculosis a Global emergency
bull Animals shed the bacilli in Milk humanrsquos get infected after drinking the unsterilized Milk
bull Pasteurization has reduced the incidence of Bovine tuberculosis
DrTVRao MD 46
Why Tuberculosis continues to be Important
bull Someone in the world is newly infected with TB bacilli every second
bull Overall one-third of the worlds population is currently infected with the TB bacillus
bull 5-10 of people who are infected with TB bacilli (but who are not infected with HIV) become sick or infectious at some time during their life People with HIV and TB infection are much more likely to develop TB
DrTVRao MD 47
bull Programme Created by DrTVRao MD for Medical and Paramedical
Students in Developing world
bull Email
bull doctortvraogmailcom
DrTVRao MD 48
![Page 16: Diagnosis of tuberculosis an Update](https://reader031.fdocuments.in/reader031/viewer/2022032113/55a62b711a28abd5138b48bb/html5/thumbnails/16.jpg)
Laboratory Diagnosis
1- Sputum smears stained by Z-N stain
Three morning successive mucopurulent sputum samples are needed to diagnose pulmonary TB
Advantage - cheap ndash rapid
- Easy to perform
- High predictive value gt 90
- Specificity of 98
Disadvantages
- sputum ( need to contain 5000-10000 AFB ml)
- Young children elderly amp HIV infected persons may not produce cavities amp sputum containing AFB
DrTVRao MD 16
2- Detecting AFB by fluorochrome stain using fluorescence microscopy
The smear may be stained by aura mine-O dye In this method the TB bacilli are stained yellow against dark background amp easily visualized using florescent microscope
Advantages
- More sensitive
- Rapid
Disadvantages
- Hazards of dye toxicity
- more expensive
- must be confirmed by Z-N stain
DrTVRao MD 17
LowensteinndashJensen mediumbull When grown on LJ
medium M tuberculosis appears as brown granular colonies (sometimes called buff rough and tough) The media must be incubated for a significant length of time usually four weeks due to the slow doubling time of M tuberculosis DrTVRao MD 18
3- Cultures on L J media
Lowenstein ndashJensen medium is an egg based media
with addition of salts 5 glycerol Malachite green
Advantages - Specificity about 99
- More sensitive (need lower no of bacilli 10-100 ml)
- Can differentiate between TB complex amp NTM using biochemical reactions
- Sensitivity tests for antituberculous drugs
( St INH Rif E)
Disadvantages Slowly growing ( up to 8 weeks )DrTVRao MD 19
Recent Methods for Diagnosis
I ndashBACTEC 460 ( rapid radiometric culture system )specimens are cultured in a liquid medium
(Middle brook7H9 broth base )containing C14 ndashlabelled palmitic acid amp PANTA antibiotic mixture
Growing mycobacteria utilize the acid releasing radioactive CO2 which is measured as growth index (GI) in the BACTEC instrument
The daily increase in GI output is directly proportional to the rate amp amount of growth in the medium
Mycobacteria Growth Indicator
Tube (MGIT)
Tube contains modified Middlebrook 7H9
broth base with OADC enrichment amp
PANTA antibiotic mixture
All types of clinical specimens pulmonary
as well as extra-pulmonary ( except
blood) could be cultured on this type of
media
The MGIT 960 System
The MGIT 960 system is a non-radiometeric
automated system that uses the MGIT media amp
sensors to detect the fluorescence
Advantages
-The system holds 960 plastic tubes which are
continuously monitored
- Early detection as the machine monitoring amp
reading the tubes every hour
Detection and identification of mycobacteria directly
from clinical samplesbull Genotypic Methods
bull 1048708 PCR
bull 1048708 LAMP
bull 1048708 TMA NAA
bull 1048708 Ligase chain reaction
bull 1048708 Phenotypic Methods
bull 1048708 FAST Plaque TB
DrTVRao MD 23
bull Essentially PCR is a way to make millions of identical copies of a specific DNA sequence which may be a gene or a part of a gene or simply a stretch of nucleotides with a known DNA sequence the function of which may be unknown
Polymerase Chain Reaction (PCR)
DrTVRao MD 24
Polymerase Chain Reaction (PCR) amp
Gene probeNucleic acid probes amp nucleic acid amplification
tests in which polymerase enzymes are used to
amplify ( make many copies of specific DNA or
RNA sequences extracted from mycobacterial
cells
Advantages
- Rapid procedure - High sensitivity (1-10
( 3 ndash 4 hours) bacilli ml sputum)
bull Interferon-γ assays measure cell-mediated immunity by quantifying IFN-γ released from sensitized T cells in whole bloodPBMCs incubated with TB antigens
Quantiferon-GOLD
DrTVRao MD 26
What Positive Skin Test ( Tuberculin Test means)
bull A positive TB skin test or TB blood test only tells that a person has been infected with TB bacteria It does not tell whether the person has latent TB infection (LTBI) or has progressed to TB disease
DrTVRao MD 27
Tuberculin TestInterpretation A positive test indicates previous exposure and
carriage of TB A negative tuberculin test excludes infection in
suspected persons Tuberculin positive persons may develop
reactivation type of TB Tuberculin negative persons are at risk of gaining
new infection False positive reactions are mainly due to
- Infection with nontuberculous mycobacteria
DrTVRao MD 28
False negative reactions may be due to-
bull False negative reactions may be due to
- Sever tuberculosis infection (Miliary TB) -Hodgkinrsquos disease
bull Corticosteroid therapy - Malnutrition -AIDS
bull Children below 5 years of age with no exposure history
bull Positive test must be regarded suspicious
DrTVRao MD 29
Tuberculin Test( Mantoux Test )
bull Test to be interpreted in relation to clinical evaluation
bull Even the induration of 5 mm to be considered positive when tested on HIV patients
bull Lacks specificity
Positive Test Means
bull This means the personrsquos body was infected with TB bacteria Additional tests are needed to determine if the person has latent TB infection or TB disease A health care worker will then provide treatment as needed
DrTVRao MD 31
Negative Test Means
bull This means the personrsquos body did not react to the test and that latent TB infection or TB disease is not likely
DrTVRao MD 32
Tuberculin Testing - Limitations
bull False positive reactions are mainly due to
bull - Infection with nontuberculous mycobacteria
bull False negative reactions may be due to
bull - Sever tuberculosis infection (Miliary TB) -Hodgkinrsquos disease
bull - Corticosteroid therapy - Malnutrition -AIDS
bull Children below 5 years of age with no exposure history
bull - Positive test must be regarded suspicious DrTVRao MD 33
Recent Methods for Diagnosis
I ndash BACTEC 460 ( rapid radiometric culture system )
Specimens are cultured in a liquid medium (Middle brook7H9 broth base )containing C14 ndash labeled palmitic acid amp PANTA antibiotic mixture
Growing mycobacteria utilize the acid releasing radioactive CO2 which is measured as growth index (GI) in the BACTEC instrument
The daily increase in GI output is directly proportional to the rate amp amount of growth in the medium
DrTVRao MD 34
TB blood testsbull TB blood tests (also called interferon-gamma
release assays or IGRAs) measure how the immune system reacts to the bacteria that cause TB An IGRA measures how strong a personrsquos immune system reacts to TB bacteria by testing the personrsquos blood in a laboratory
bull Two IGRAs are approved by the US Food and Drug Administration (FDA) and are available in the United States
DrTVRao MD 35
Positive IGRAbull This means that the
person has been infected with TB bacteria Additional tests are needed to determine if the person has latent TB infection or TB disease A health care worker will then provide treatment as needed
DrTVRao MD 36
Negative IGRA
bull This means that the personrsquos blood did not react to the test and that latent TB infection or TB disease is not likely
DrTVRao MD 37
IGRAs are the preferred method of TB infection testing for the following
People who have received bacilli ChalmettendashGueacuterin (BCG) BCG is a vaccine for TB disease People who have a difficult time returning for a second appointment to look for a reaction to the TST
There is no problem with repeated IGRAs
DrTVRao MD 38
III Polymerase Chain Reaction
(PCR) amp Gene probeNucleic acid probes amp nucleic acid amplification
tests in which polymerase enzymes are used to
amplify ( make many copies of specific DNA or
RNA sequences extracted from mycobacterial
cells
Advantages
- Rapid procedure - High sensitivity (1-10
( 3 ndash 4 hours) bacilli ml sputum)
DrTVRao MD 39
Molecular DR testing is particularly useful for
bull Patients suspected or at high risk of having drug-resistant TBvery ill patients for whom drug-susceptibility information might alter case management decisions such as patients who do not get better while taking standard first-line therapy
DrTVRao MD 40
Detection of MDR Tuberculosis
bull Very ill patients for whom drug-susceptibility information might alter case management decisions such as patients who do not get better while taking standard first-line therapy
DrTVRao MD 41
Detection of MDR Tuberculosis
bull outbreak or contact investigations when drug resistance is suspected in the source case or in some severely immunocompromised persons such as HIV-infected persons or those receiving dialysis in which knowledge of drug-susceptibility would be a significant benefit and affect preventive therapy decisions
DrTVRao MD 42
Tuberculosis and HIV infection
bull HIV association has become a threat to the developed countries too
bull HIV association will lead to rapid spread of tuberculosis
DrTVRao MD 43
HIV Considerations
bull HIV is the strongest risk factor for progression to active disease
bull HIV kills CD4+ T Helper cells which normally inhibit M tuberculosis
bull HIV interferes with PPD skin test
bull Protease inhibitors interfere with rifampin
DrTVRao MD 44
Epidemiologybull An ancient disease called as white plague
bull 13 of the world population is infected
bull 2 billion infected
bull Each year 9 lakhs to 1 million are infected
bull Poor nations phase the burnt of the disease
bull In developing world gt 4o of the population is effected
bull 15 million suffer the disease
bull 3 million are highly infective
DrTVRao MD 45
MDR tuberculosis
bull Multidrug resistant tuberculosis has become a global threat
bull In 1993 WHO declared Tuberculosis a Global emergency
bull Animals shed the bacilli in Milk humanrsquos get infected after drinking the unsterilized Milk
bull Pasteurization has reduced the incidence of Bovine tuberculosis
DrTVRao MD 46
Why Tuberculosis continues to be Important
bull Someone in the world is newly infected with TB bacilli every second
bull Overall one-third of the worlds population is currently infected with the TB bacillus
bull 5-10 of people who are infected with TB bacilli (but who are not infected with HIV) become sick or infectious at some time during their life People with HIV and TB infection are much more likely to develop TB
DrTVRao MD 47
bull Programme Created by DrTVRao MD for Medical and Paramedical
Students in Developing world
bull Email
bull doctortvraogmailcom
DrTVRao MD 48
![Page 17: Diagnosis of tuberculosis an Update](https://reader031.fdocuments.in/reader031/viewer/2022032113/55a62b711a28abd5138b48bb/html5/thumbnails/17.jpg)
2- Detecting AFB by fluorochrome stain using fluorescence microscopy
The smear may be stained by aura mine-O dye In this method the TB bacilli are stained yellow against dark background amp easily visualized using florescent microscope
Advantages
- More sensitive
- Rapid
Disadvantages
- Hazards of dye toxicity
- more expensive
- must be confirmed by Z-N stain
DrTVRao MD 17
LowensteinndashJensen mediumbull When grown on LJ
medium M tuberculosis appears as brown granular colonies (sometimes called buff rough and tough) The media must be incubated for a significant length of time usually four weeks due to the slow doubling time of M tuberculosis DrTVRao MD 18
3- Cultures on L J media
Lowenstein ndashJensen medium is an egg based media
with addition of salts 5 glycerol Malachite green
Advantages - Specificity about 99
- More sensitive (need lower no of bacilli 10-100 ml)
- Can differentiate between TB complex amp NTM using biochemical reactions
- Sensitivity tests for antituberculous drugs
( St INH Rif E)
Disadvantages Slowly growing ( up to 8 weeks )DrTVRao MD 19
Recent Methods for Diagnosis
I ndashBACTEC 460 ( rapid radiometric culture system )specimens are cultured in a liquid medium
(Middle brook7H9 broth base )containing C14 ndashlabelled palmitic acid amp PANTA antibiotic mixture
Growing mycobacteria utilize the acid releasing radioactive CO2 which is measured as growth index (GI) in the BACTEC instrument
The daily increase in GI output is directly proportional to the rate amp amount of growth in the medium
Mycobacteria Growth Indicator
Tube (MGIT)
Tube contains modified Middlebrook 7H9
broth base with OADC enrichment amp
PANTA antibiotic mixture
All types of clinical specimens pulmonary
as well as extra-pulmonary ( except
blood) could be cultured on this type of
media
The MGIT 960 System
The MGIT 960 system is a non-radiometeric
automated system that uses the MGIT media amp
sensors to detect the fluorescence
Advantages
-The system holds 960 plastic tubes which are
continuously monitored
- Early detection as the machine monitoring amp
reading the tubes every hour
Detection and identification of mycobacteria directly
from clinical samplesbull Genotypic Methods
bull 1048708 PCR
bull 1048708 LAMP
bull 1048708 TMA NAA
bull 1048708 Ligase chain reaction
bull 1048708 Phenotypic Methods
bull 1048708 FAST Plaque TB
DrTVRao MD 23
bull Essentially PCR is a way to make millions of identical copies of a specific DNA sequence which may be a gene or a part of a gene or simply a stretch of nucleotides with a known DNA sequence the function of which may be unknown
Polymerase Chain Reaction (PCR)
DrTVRao MD 24
Polymerase Chain Reaction (PCR) amp
Gene probeNucleic acid probes amp nucleic acid amplification
tests in which polymerase enzymes are used to
amplify ( make many copies of specific DNA or
RNA sequences extracted from mycobacterial
cells
Advantages
- Rapid procedure - High sensitivity (1-10
( 3 ndash 4 hours) bacilli ml sputum)
bull Interferon-γ assays measure cell-mediated immunity by quantifying IFN-γ released from sensitized T cells in whole bloodPBMCs incubated with TB antigens
Quantiferon-GOLD
DrTVRao MD 26
What Positive Skin Test ( Tuberculin Test means)
bull A positive TB skin test or TB blood test only tells that a person has been infected with TB bacteria It does not tell whether the person has latent TB infection (LTBI) or has progressed to TB disease
DrTVRao MD 27
Tuberculin TestInterpretation A positive test indicates previous exposure and
carriage of TB A negative tuberculin test excludes infection in
suspected persons Tuberculin positive persons may develop
reactivation type of TB Tuberculin negative persons are at risk of gaining
new infection False positive reactions are mainly due to
- Infection with nontuberculous mycobacteria
DrTVRao MD 28
False negative reactions may be due to-
bull False negative reactions may be due to
- Sever tuberculosis infection (Miliary TB) -Hodgkinrsquos disease
bull Corticosteroid therapy - Malnutrition -AIDS
bull Children below 5 years of age with no exposure history
bull Positive test must be regarded suspicious
DrTVRao MD 29
Tuberculin Test( Mantoux Test )
bull Test to be interpreted in relation to clinical evaluation
bull Even the induration of 5 mm to be considered positive when tested on HIV patients
bull Lacks specificity
Positive Test Means
bull This means the personrsquos body was infected with TB bacteria Additional tests are needed to determine if the person has latent TB infection or TB disease A health care worker will then provide treatment as needed
DrTVRao MD 31
Negative Test Means
bull This means the personrsquos body did not react to the test and that latent TB infection or TB disease is not likely
DrTVRao MD 32
Tuberculin Testing - Limitations
bull False positive reactions are mainly due to
bull - Infection with nontuberculous mycobacteria
bull False negative reactions may be due to
bull - Sever tuberculosis infection (Miliary TB) -Hodgkinrsquos disease
bull - Corticosteroid therapy - Malnutrition -AIDS
bull Children below 5 years of age with no exposure history
bull - Positive test must be regarded suspicious DrTVRao MD 33
Recent Methods for Diagnosis
I ndash BACTEC 460 ( rapid radiometric culture system )
Specimens are cultured in a liquid medium (Middle brook7H9 broth base )containing C14 ndash labeled palmitic acid amp PANTA antibiotic mixture
Growing mycobacteria utilize the acid releasing radioactive CO2 which is measured as growth index (GI) in the BACTEC instrument
The daily increase in GI output is directly proportional to the rate amp amount of growth in the medium
DrTVRao MD 34
TB blood testsbull TB blood tests (also called interferon-gamma
release assays or IGRAs) measure how the immune system reacts to the bacteria that cause TB An IGRA measures how strong a personrsquos immune system reacts to TB bacteria by testing the personrsquos blood in a laboratory
bull Two IGRAs are approved by the US Food and Drug Administration (FDA) and are available in the United States
DrTVRao MD 35
Positive IGRAbull This means that the
person has been infected with TB bacteria Additional tests are needed to determine if the person has latent TB infection or TB disease A health care worker will then provide treatment as needed
DrTVRao MD 36
Negative IGRA
bull This means that the personrsquos blood did not react to the test and that latent TB infection or TB disease is not likely
DrTVRao MD 37
IGRAs are the preferred method of TB infection testing for the following
People who have received bacilli ChalmettendashGueacuterin (BCG) BCG is a vaccine for TB disease People who have a difficult time returning for a second appointment to look for a reaction to the TST
There is no problem with repeated IGRAs
DrTVRao MD 38
III Polymerase Chain Reaction
(PCR) amp Gene probeNucleic acid probes amp nucleic acid amplification
tests in which polymerase enzymes are used to
amplify ( make many copies of specific DNA or
RNA sequences extracted from mycobacterial
cells
Advantages
- Rapid procedure - High sensitivity (1-10
( 3 ndash 4 hours) bacilli ml sputum)
DrTVRao MD 39
Molecular DR testing is particularly useful for
bull Patients suspected or at high risk of having drug-resistant TBvery ill patients for whom drug-susceptibility information might alter case management decisions such as patients who do not get better while taking standard first-line therapy
DrTVRao MD 40
Detection of MDR Tuberculosis
bull Very ill patients for whom drug-susceptibility information might alter case management decisions such as patients who do not get better while taking standard first-line therapy
DrTVRao MD 41
Detection of MDR Tuberculosis
bull outbreak or contact investigations when drug resistance is suspected in the source case or in some severely immunocompromised persons such as HIV-infected persons or those receiving dialysis in which knowledge of drug-susceptibility would be a significant benefit and affect preventive therapy decisions
DrTVRao MD 42
Tuberculosis and HIV infection
bull HIV association has become a threat to the developed countries too
bull HIV association will lead to rapid spread of tuberculosis
DrTVRao MD 43
HIV Considerations
bull HIV is the strongest risk factor for progression to active disease
bull HIV kills CD4+ T Helper cells which normally inhibit M tuberculosis
bull HIV interferes with PPD skin test
bull Protease inhibitors interfere with rifampin
DrTVRao MD 44
Epidemiologybull An ancient disease called as white plague
bull 13 of the world population is infected
bull 2 billion infected
bull Each year 9 lakhs to 1 million are infected
bull Poor nations phase the burnt of the disease
bull In developing world gt 4o of the population is effected
bull 15 million suffer the disease
bull 3 million are highly infective
DrTVRao MD 45
MDR tuberculosis
bull Multidrug resistant tuberculosis has become a global threat
bull In 1993 WHO declared Tuberculosis a Global emergency
bull Animals shed the bacilli in Milk humanrsquos get infected after drinking the unsterilized Milk
bull Pasteurization has reduced the incidence of Bovine tuberculosis
DrTVRao MD 46
Why Tuberculosis continues to be Important
bull Someone in the world is newly infected with TB bacilli every second
bull Overall one-third of the worlds population is currently infected with the TB bacillus
bull 5-10 of people who are infected with TB bacilli (but who are not infected with HIV) become sick or infectious at some time during their life People with HIV and TB infection are much more likely to develop TB
DrTVRao MD 47
bull Programme Created by DrTVRao MD for Medical and Paramedical
Students in Developing world
bull Email
bull doctortvraogmailcom
DrTVRao MD 48
![Page 18: Diagnosis of tuberculosis an Update](https://reader031.fdocuments.in/reader031/viewer/2022032113/55a62b711a28abd5138b48bb/html5/thumbnails/18.jpg)
LowensteinndashJensen mediumbull When grown on LJ
medium M tuberculosis appears as brown granular colonies (sometimes called buff rough and tough) The media must be incubated for a significant length of time usually four weeks due to the slow doubling time of M tuberculosis DrTVRao MD 18
3- Cultures on L J media
Lowenstein ndashJensen medium is an egg based media
with addition of salts 5 glycerol Malachite green
Advantages - Specificity about 99
- More sensitive (need lower no of bacilli 10-100 ml)
- Can differentiate between TB complex amp NTM using biochemical reactions
- Sensitivity tests for antituberculous drugs
( St INH Rif E)
Disadvantages Slowly growing ( up to 8 weeks )DrTVRao MD 19
Recent Methods for Diagnosis
I ndashBACTEC 460 ( rapid radiometric culture system )specimens are cultured in a liquid medium
(Middle brook7H9 broth base )containing C14 ndashlabelled palmitic acid amp PANTA antibiotic mixture
Growing mycobacteria utilize the acid releasing radioactive CO2 which is measured as growth index (GI) in the BACTEC instrument
The daily increase in GI output is directly proportional to the rate amp amount of growth in the medium
Mycobacteria Growth Indicator
Tube (MGIT)
Tube contains modified Middlebrook 7H9
broth base with OADC enrichment amp
PANTA antibiotic mixture
All types of clinical specimens pulmonary
as well as extra-pulmonary ( except
blood) could be cultured on this type of
media
The MGIT 960 System
The MGIT 960 system is a non-radiometeric
automated system that uses the MGIT media amp
sensors to detect the fluorescence
Advantages
-The system holds 960 plastic tubes which are
continuously monitored
- Early detection as the machine monitoring amp
reading the tubes every hour
Detection and identification of mycobacteria directly
from clinical samplesbull Genotypic Methods
bull 1048708 PCR
bull 1048708 LAMP
bull 1048708 TMA NAA
bull 1048708 Ligase chain reaction
bull 1048708 Phenotypic Methods
bull 1048708 FAST Plaque TB
DrTVRao MD 23
bull Essentially PCR is a way to make millions of identical copies of a specific DNA sequence which may be a gene or a part of a gene or simply a stretch of nucleotides with a known DNA sequence the function of which may be unknown
Polymerase Chain Reaction (PCR)
DrTVRao MD 24
Polymerase Chain Reaction (PCR) amp
Gene probeNucleic acid probes amp nucleic acid amplification
tests in which polymerase enzymes are used to
amplify ( make many copies of specific DNA or
RNA sequences extracted from mycobacterial
cells
Advantages
- Rapid procedure - High sensitivity (1-10
( 3 ndash 4 hours) bacilli ml sputum)
bull Interferon-γ assays measure cell-mediated immunity by quantifying IFN-γ released from sensitized T cells in whole bloodPBMCs incubated with TB antigens
Quantiferon-GOLD
DrTVRao MD 26
What Positive Skin Test ( Tuberculin Test means)
bull A positive TB skin test or TB blood test only tells that a person has been infected with TB bacteria It does not tell whether the person has latent TB infection (LTBI) or has progressed to TB disease
DrTVRao MD 27
Tuberculin TestInterpretation A positive test indicates previous exposure and
carriage of TB A negative tuberculin test excludes infection in
suspected persons Tuberculin positive persons may develop
reactivation type of TB Tuberculin negative persons are at risk of gaining
new infection False positive reactions are mainly due to
- Infection with nontuberculous mycobacteria
DrTVRao MD 28
False negative reactions may be due to-
bull False negative reactions may be due to
- Sever tuberculosis infection (Miliary TB) -Hodgkinrsquos disease
bull Corticosteroid therapy - Malnutrition -AIDS
bull Children below 5 years of age with no exposure history
bull Positive test must be regarded suspicious
DrTVRao MD 29
Tuberculin Test( Mantoux Test )
bull Test to be interpreted in relation to clinical evaluation
bull Even the induration of 5 mm to be considered positive when tested on HIV patients
bull Lacks specificity
Positive Test Means
bull This means the personrsquos body was infected with TB bacteria Additional tests are needed to determine if the person has latent TB infection or TB disease A health care worker will then provide treatment as needed
DrTVRao MD 31
Negative Test Means
bull This means the personrsquos body did not react to the test and that latent TB infection or TB disease is not likely
DrTVRao MD 32
Tuberculin Testing - Limitations
bull False positive reactions are mainly due to
bull - Infection with nontuberculous mycobacteria
bull False negative reactions may be due to
bull - Sever tuberculosis infection (Miliary TB) -Hodgkinrsquos disease
bull - Corticosteroid therapy - Malnutrition -AIDS
bull Children below 5 years of age with no exposure history
bull - Positive test must be regarded suspicious DrTVRao MD 33
Recent Methods for Diagnosis
I ndash BACTEC 460 ( rapid radiometric culture system )
Specimens are cultured in a liquid medium (Middle brook7H9 broth base )containing C14 ndash labeled palmitic acid amp PANTA antibiotic mixture
Growing mycobacteria utilize the acid releasing radioactive CO2 which is measured as growth index (GI) in the BACTEC instrument
The daily increase in GI output is directly proportional to the rate amp amount of growth in the medium
DrTVRao MD 34
TB blood testsbull TB blood tests (also called interferon-gamma
release assays or IGRAs) measure how the immune system reacts to the bacteria that cause TB An IGRA measures how strong a personrsquos immune system reacts to TB bacteria by testing the personrsquos blood in a laboratory
bull Two IGRAs are approved by the US Food and Drug Administration (FDA) and are available in the United States
DrTVRao MD 35
Positive IGRAbull This means that the
person has been infected with TB bacteria Additional tests are needed to determine if the person has latent TB infection or TB disease A health care worker will then provide treatment as needed
DrTVRao MD 36
Negative IGRA
bull This means that the personrsquos blood did not react to the test and that latent TB infection or TB disease is not likely
DrTVRao MD 37
IGRAs are the preferred method of TB infection testing for the following
People who have received bacilli ChalmettendashGueacuterin (BCG) BCG is a vaccine for TB disease People who have a difficult time returning for a second appointment to look for a reaction to the TST
There is no problem with repeated IGRAs
DrTVRao MD 38
III Polymerase Chain Reaction
(PCR) amp Gene probeNucleic acid probes amp nucleic acid amplification
tests in which polymerase enzymes are used to
amplify ( make many copies of specific DNA or
RNA sequences extracted from mycobacterial
cells
Advantages
- Rapid procedure - High sensitivity (1-10
( 3 ndash 4 hours) bacilli ml sputum)
DrTVRao MD 39
Molecular DR testing is particularly useful for
bull Patients suspected or at high risk of having drug-resistant TBvery ill patients for whom drug-susceptibility information might alter case management decisions such as patients who do not get better while taking standard first-line therapy
DrTVRao MD 40
Detection of MDR Tuberculosis
bull Very ill patients for whom drug-susceptibility information might alter case management decisions such as patients who do not get better while taking standard first-line therapy
DrTVRao MD 41
Detection of MDR Tuberculosis
bull outbreak or contact investigations when drug resistance is suspected in the source case or in some severely immunocompromised persons such as HIV-infected persons or those receiving dialysis in which knowledge of drug-susceptibility would be a significant benefit and affect preventive therapy decisions
DrTVRao MD 42
Tuberculosis and HIV infection
bull HIV association has become a threat to the developed countries too
bull HIV association will lead to rapid spread of tuberculosis
DrTVRao MD 43
HIV Considerations
bull HIV is the strongest risk factor for progression to active disease
bull HIV kills CD4+ T Helper cells which normally inhibit M tuberculosis
bull HIV interferes with PPD skin test
bull Protease inhibitors interfere with rifampin
DrTVRao MD 44
Epidemiologybull An ancient disease called as white plague
bull 13 of the world population is infected
bull 2 billion infected
bull Each year 9 lakhs to 1 million are infected
bull Poor nations phase the burnt of the disease
bull In developing world gt 4o of the population is effected
bull 15 million suffer the disease
bull 3 million are highly infective
DrTVRao MD 45
MDR tuberculosis
bull Multidrug resistant tuberculosis has become a global threat
bull In 1993 WHO declared Tuberculosis a Global emergency
bull Animals shed the bacilli in Milk humanrsquos get infected after drinking the unsterilized Milk
bull Pasteurization has reduced the incidence of Bovine tuberculosis
DrTVRao MD 46
Why Tuberculosis continues to be Important
bull Someone in the world is newly infected with TB bacilli every second
bull Overall one-third of the worlds population is currently infected with the TB bacillus
bull 5-10 of people who are infected with TB bacilli (but who are not infected with HIV) become sick or infectious at some time during their life People with HIV and TB infection are much more likely to develop TB
DrTVRao MD 47
bull Programme Created by DrTVRao MD for Medical and Paramedical
Students in Developing world
bull Email
bull doctortvraogmailcom
DrTVRao MD 48
![Page 19: Diagnosis of tuberculosis an Update](https://reader031.fdocuments.in/reader031/viewer/2022032113/55a62b711a28abd5138b48bb/html5/thumbnails/19.jpg)
3- Cultures on L J media
Lowenstein ndashJensen medium is an egg based media
with addition of salts 5 glycerol Malachite green
Advantages - Specificity about 99
- More sensitive (need lower no of bacilli 10-100 ml)
- Can differentiate between TB complex amp NTM using biochemical reactions
- Sensitivity tests for antituberculous drugs
( St INH Rif E)
Disadvantages Slowly growing ( up to 8 weeks )DrTVRao MD 19
Recent Methods for Diagnosis
I ndashBACTEC 460 ( rapid radiometric culture system )specimens are cultured in a liquid medium
(Middle brook7H9 broth base )containing C14 ndashlabelled palmitic acid amp PANTA antibiotic mixture
Growing mycobacteria utilize the acid releasing radioactive CO2 which is measured as growth index (GI) in the BACTEC instrument
The daily increase in GI output is directly proportional to the rate amp amount of growth in the medium
Mycobacteria Growth Indicator
Tube (MGIT)
Tube contains modified Middlebrook 7H9
broth base with OADC enrichment amp
PANTA antibiotic mixture
All types of clinical specimens pulmonary
as well as extra-pulmonary ( except
blood) could be cultured on this type of
media
The MGIT 960 System
The MGIT 960 system is a non-radiometeric
automated system that uses the MGIT media amp
sensors to detect the fluorescence
Advantages
-The system holds 960 plastic tubes which are
continuously monitored
- Early detection as the machine monitoring amp
reading the tubes every hour
Detection and identification of mycobacteria directly
from clinical samplesbull Genotypic Methods
bull 1048708 PCR
bull 1048708 LAMP
bull 1048708 TMA NAA
bull 1048708 Ligase chain reaction
bull 1048708 Phenotypic Methods
bull 1048708 FAST Plaque TB
DrTVRao MD 23
bull Essentially PCR is a way to make millions of identical copies of a specific DNA sequence which may be a gene or a part of a gene or simply a stretch of nucleotides with a known DNA sequence the function of which may be unknown
Polymerase Chain Reaction (PCR)
DrTVRao MD 24
Polymerase Chain Reaction (PCR) amp
Gene probeNucleic acid probes amp nucleic acid amplification
tests in which polymerase enzymes are used to
amplify ( make many copies of specific DNA or
RNA sequences extracted from mycobacterial
cells
Advantages
- Rapid procedure - High sensitivity (1-10
( 3 ndash 4 hours) bacilli ml sputum)
bull Interferon-γ assays measure cell-mediated immunity by quantifying IFN-γ released from sensitized T cells in whole bloodPBMCs incubated with TB antigens
Quantiferon-GOLD
DrTVRao MD 26
What Positive Skin Test ( Tuberculin Test means)
bull A positive TB skin test or TB blood test only tells that a person has been infected with TB bacteria It does not tell whether the person has latent TB infection (LTBI) or has progressed to TB disease
DrTVRao MD 27
Tuberculin TestInterpretation A positive test indicates previous exposure and
carriage of TB A negative tuberculin test excludes infection in
suspected persons Tuberculin positive persons may develop
reactivation type of TB Tuberculin negative persons are at risk of gaining
new infection False positive reactions are mainly due to
- Infection with nontuberculous mycobacteria
DrTVRao MD 28
False negative reactions may be due to-
bull False negative reactions may be due to
- Sever tuberculosis infection (Miliary TB) -Hodgkinrsquos disease
bull Corticosteroid therapy - Malnutrition -AIDS
bull Children below 5 years of age with no exposure history
bull Positive test must be regarded suspicious
DrTVRao MD 29
Tuberculin Test( Mantoux Test )
bull Test to be interpreted in relation to clinical evaluation
bull Even the induration of 5 mm to be considered positive when tested on HIV patients
bull Lacks specificity
Positive Test Means
bull This means the personrsquos body was infected with TB bacteria Additional tests are needed to determine if the person has latent TB infection or TB disease A health care worker will then provide treatment as needed
DrTVRao MD 31
Negative Test Means
bull This means the personrsquos body did not react to the test and that latent TB infection or TB disease is not likely
DrTVRao MD 32
Tuberculin Testing - Limitations
bull False positive reactions are mainly due to
bull - Infection with nontuberculous mycobacteria
bull False negative reactions may be due to
bull - Sever tuberculosis infection (Miliary TB) -Hodgkinrsquos disease
bull - Corticosteroid therapy - Malnutrition -AIDS
bull Children below 5 years of age with no exposure history
bull - Positive test must be regarded suspicious DrTVRao MD 33
Recent Methods for Diagnosis
I ndash BACTEC 460 ( rapid radiometric culture system )
Specimens are cultured in a liquid medium (Middle brook7H9 broth base )containing C14 ndash labeled palmitic acid amp PANTA antibiotic mixture
Growing mycobacteria utilize the acid releasing radioactive CO2 which is measured as growth index (GI) in the BACTEC instrument
The daily increase in GI output is directly proportional to the rate amp amount of growth in the medium
DrTVRao MD 34
TB blood testsbull TB blood tests (also called interferon-gamma
release assays or IGRAs) measure how the immune system reacts to the bacteria that cause TB An IGRA measures how strong a personrsquos immune system reacts to TB bacteria by testing the personrsquos blood in a laboratory
bull Two IGRAs are approved by the US Food and Drug Administration (FDA) and are available in the United States
DrTVRao MD 35
Positive IGRAbull This means that the
person has been infected with TB bacteria Additional tests are needed to determine if the person has latent TB infection or TB disease A health care worker will then provide treatment as needed
DrTVRao MD 36
Negative IGRA
bull This means that the personrsquos blood did not react to the test and that latent TB infection or TB disease is not likely
DrTVRao MD 37
IGRAs are the preferred method of TB infection testing for the following
People who have received bacilli ChalmettendashGueacuterin (BCG) BCG is a vaccine for TB disease People who have a difficult time returning for a second appointment to look for a reaction to the TST
There is no problem with repeated IGRAs
DrTVRao MD 38
III Polymerase Chain Reaction
(PCR) amp Gene probeNucleic acid probes amp nucleic acid amplification
tests in which polymerase enzymes are used to
amplify ( make many copies of specific DNA or
RNA sequences extracted from mycobacterial
cells
Advantages
- Rapid procedure - High sensitivity (1-10
( 3 ndash 4 hours) bacilli ml sputum)
DrTVRao MD 39
Molecular DR testing is particularly useful for
bull Patients suspected or at high risk of having drug-resistant TBvery ill patients for whom drug-susceptibility information might alter case management decisions such as patients who do not get better while taking standard first-line therapy
DrTVRao MD 40
Detection of MDR Tuberculosis
bull Very ill patients for whom drug-susceptibility information might alter case management decisions such as patients who do not get better while taking standard first-line therapy
DrTVRao MD 41
Detection of MDR Tuberculosis
bull outbreak or contact investigations when drug resistance is suspected in the source case or in some severely immunocompromised persons such as HIV-infected persons or those receiving dialysis in which knowledge of drug-susceptibility would be a significant benefit and affect preventive therapy decisions
DrTVRao MD 42
Tuberculosis and HIV infection
bull HIV association has become a threat to the developed countries too
bull HIV association will lead to rapid spread of tuberculosis
DrTVRao MD 43
HIV Considerations
bull HIV is the strongest risk factor for progression to active disease
bull HIV kills CD4+ T Helper cells which normally inhibit M tuberculosis
bull HIV interferes with PPD skin test
bull Protease inhibitors interfere with rifampin
DrTVRao MD 44
Epidemiologybull An ancient disease called as white plague
bull 13 of the world population is infected
bull 2 billion infected
bull Each year 9 lakhs to 1 million are infected
bull Poor nations phase the burnt of the disease
bull In developing world gt 4o of the population is effected
bull 15 million suffer the disease
bull 3 million are highly infective
DrTVRao MD 45
MDR tuberculosis
bull Multidrug resistant tuberculosis has become a global threat
bull In 1993 WHO declared Tuberculosis a Global emergency
bull Animals shed the bacilli in Milk humanrsquos get infected after drinking the unsterilized Milk
bull Pasteurization has reduced the incidence of Bovine tuberculosis
DrTVRao MD 46
Why Tuberculosis continues to be Important
bull Someone in the world is newly infected with TB bacilli every second
bull Overall one-third of the worlds population is currently infected with the TB bacillus
bull 5-10 of people who are infected with TB bacilli (but who are not infected with HIV) become sick or infectious at some time during their life People with HIV and TB infection are much more likely to develop TB
DrTVRao MD 47
bull Programme Created by DrTVRao MD for Medical and Paramedical
Students in Developing world
bull Email
bull doctortvraogmailcom
DrTVRao MD 48
![Page 20: Diagnosis of tuberculosis an Update](https://reader031.fdocuments.in/reader031/viewer/2022032113/55a62b711a28abd5138b48bb/html5/thumbnails/20.jpg)
Recent Methods for Diagnosis
I ndashBACTEC 460 ( rapid radiometric culture system )specimens are cultured in a liquid medium
(Middle brook7H9 broth base )containing C14 ndashlabelled palmitic acid amp PANTA antibiotic mixture
Growing mycobacteria utilize the acid releasing radioactive CO2 which is measured as growth index (GI) in the BACTEC instrument
The daily increase in GI output is directly proportional to the rate amp amount of growth in the medium
Mycobacteria Growth Indicator
Tube (MGIT)
Tube contains modified Middlebrook 7H9
broth base with OADC enrichment amp
PANTA antibiotic mixture
All types of clinical specimens pulmonary
as well as extra-pulmonary ( except
blood) could be cultured on this type of
media
The MGIT 960 System
The MGIT 960 system is a non-radiometeric
automated system that uses the MGIT media amp
sensors to detect the fluorescence
Advantages
-The system holds 960 plastic tubes which are
continuously monitored
- Early detection as the machine monitoring amp
reading the tubes every hour
Detection and identification of mycobacteria directly
from clinical samplesbull Genotypic Methods
bull 1048708 PCR
bull 1048708 LAMP
bull 1048708 TMA NAA
bull 1048708 Ligase chain reaction
bull 1048708 Phenotypic Methods
bull 1048708 FAST Plaque TB
DrTVRao MD 23
bull Essentially PCR is a way to make millions of identical copies of a specific DNA sequence which may be a gene or a part of a gene or simply a stretch of nucleotides with a known DNA sequence the function of which may be unknown
Polymerase Chain Reaction (PCR)
DrTVRao MD 24
Polymerase Chain Reaction (PCR) amp
Gene probeNucleic acid probes amp nucleic acid amplification
tests in which polymerase enzymes are used to
amplify ( make many copies of specific DNA or
RNA sequences extracted from mycobacterial
cells
Advantages
- Rapid procedure - High sensitivity (1-10
( 3 ndash 4 hours) bacilli ml sputum)
bull Interferon-γ assays measure cell-mediated immunity by quantifying IFN-γ released from sensitized T cells in whole bloodPBMCs incubated with TB antigens
Quantiferon-GOLD
DrTVRao MD 26
What Positive Skin Test ( Tuberculin Test means)
bull A positive TB skin test or TB blood test only tells that a person has been infected with TB bacteria It does not tell whether the person has latent TB infection (LTBI) or has progressed to TB disease
DrTVRao MD 27
Tuberculin TestInterpretation A positive test indicates previous exposure and
carriage of TB A negative tuberculin test excludes infection in
suspected persons Tuberculin positive persons may develop
reactivation type of TB Tuberculin negative persons are at risk of gaining
new infection False positive reactions are mainly due to
- Infection with nontuberculous mycobacteria
DrTVRao MD 28
False negative reactions may be due to-
bull False negative reactions may be due to
- Sever tuberculosis infection (Miliary TB) -Hodgkinrsquos disease
bull Corticosteroid therapy - Malnutrition -AIDS
bull Children below 5 years of age with no exposure history
bull Positive test must be regarded suspicious
DrTVRao MD 29
Tuberculin Test( Mantoux Test )
bull Test to be interpreted in relation to clinical evaluation
bull Even the induration of 5 mm to be considered positive when tested on HIV patients
bull Lacks specificity
Positive Test Means
bull This means the personrsquos body was infected with TB bacteria Additional tests are needed to determine if the person has latent TB infection or TB disease A health care worker will then provide treatment as needed
DrTVRao MD 31
Negative Test Means
bull This means the personrsquos body did not react to the test and that latent TB infection or TB disease is not likely
DrTVRao MD 32
Tuberculin Testing - Limitations
bull False positive reactions are mainly due to
bull - Infection with nontuberculous mycobacteria
bull False negative reactions may be due to
bull - Sever tuberculosis infection (Miliary TB) -Hodgkinrsquos disease
bull - Corticosteroid therapy - Malnutrition -AIDS
bull Children below 5 years of age with no exposure history
bull - Positive test must be regarded suspicious DrTVRao MD 33
Recent Methods for Diagnosis
I ndash BACTEC 460 ( rapid radiometric culture system )
Specimens are cultured in a liquid medium (Middle brook7H9 broth base )containing C14 ndash labeled palmitic acid amp PANTA antibiotic mixture
Growing mycobacteria utilize the acid releasing radioactive CO2 which is measured as growth index (GI) in the BACTEC instrument
The daily increase in GI output is directly proportional to the rate amp amount of growth in the medium
DrTVRao MD 34
TB blood testsbull TB blood tests (also called interferon-gamma
release assays or IGRAs) measure how the immune system reacts to the bacteria that cause TB An IGRA measures how strong a personrsquos immune system reacts to TB bacteria by testing the personrsquos blood in a laboratory
bull Two IGRAs are approved by the US Food and Drug Administration (FDA) and are available in the United States
DrTVRao MD 35
Positive IGRAbull This means that the
person has been infected with TB bacteria Additional tests are needed to determine if the person has latent TB infection or TB disease A health care worker will then provide treatment as needed
DrTVRao MD 36
Negative IGRA
bull This means that the personrsquos blood did not react to the test and that latent TB infection or TB disease is not likely
DrTVRao MD 37
IGRAs are the preferred method of TB infection testing for the following
People who have received bacilli ChalmettendashGueacuterin (BCG) BCG is a vaccine for TB disease People who have a difficult time returning for a second appointment to look for a reaction to the TST
There is no problem with repeated IGRAs
DrTVRao MD 38
III Polymerase Chain Reaction
(PCR) amp Gene probeNucleic acid probes amp nucleic acid amplification
tests in which polymerase enzymes are used to
amplify ( make many copies of specific DNA or
RNA sequences extracted from mycobacterial
cells
Advantages
- Rapid procedure - High sensitivity (1-10
( 3 ndash 4 hours) bacilli ml sputum)
DrTVRao MD 39
Molecular DR testing is particularly useful for
bull Patients suspected or at high risk of having drug-resistant TBvery ill patients for whom drug-susceptibility information might alter case management decisions such as patients who do not get better while taking standard first-line therapy
DrTVRao MD 40
Detection of MDR Tuberculosis
bull Very ill patients for whom drug-susceptibility information might alter case management decisions such as patients who do not get better while taking standard first-line therapy
DrTVRao MD 41
Detection of MDR Tuberculosis
bull outbreak or contact investigations when drug resistance is suspected in the source case or in some severely immunocompromised persons such as HIV-infected persons or those receiving dialysis in which knowledge of drug-susceptibility would be a significant benefit and affect preventive therapy decisions
DrTVRao MD 42
Tuberculosis and HIV infection
bull HIV association has become a threat to the developed countries too
bull HIV association will lead to rapid spread of tuberculosis
DrTVRao MD 43
HIV Considerations
bull HIV is the strongest risk factor for progression to active disease
bull HIV kills CD4+ T Helper cells which normally inhibit M tuberculosis
bull HIV interferes with PPD skin test
bull Protease inhibitors interfere with rifampin
DrTVRao MD 44
Epidemiologybull An ancient disease called as white plague
bull 13 of the world population is infected
bull 2 billion infected
bull Each year 9 lakhs to 1 million are infected
bull Poor nations phase the burnt of the disease
bull In developing world gt 4o of the population is effected
bull 15 million suffer the disease
bull 3 million are highly infective
DrTVRao MD 45
MDR tuberculosis
bull Multidrug resistant tuberculosis has become a global threat
bull In 1993 WHO declared Tuberculosis a Global emergency
bull Animals shed the bacilli in Milk humanrsquos get infected after drinking the unsterilized Milk
bull Pasteurization has reduced the incidence of Bovine tuberculosis
DrTVRao MD 46
Why Tuberculosis continues to be Important
bull Someone in the world is newly infected with TB bacilli every second
bull Overall one-third of the worlds population is currently infected with the TB bacillus
bull 5-10 of people who are infected with TB bacilli (but who are not infected with HIV) become sick or infectious at some time during their life People with HIV and TB infection are much more likely to develop TB
DrTVRao MD 47
bull Programme Created by DrTVRao MD for Medical and Paramedical
Students in Developing world
bull Email
bull doctortvraogmailcom
DrTVRao MD 48
![Page 21: Diagnosis of tuberculosis an Update](https://reader031.fdocuments.in/reader031/viewer/2022032113/55a62b711a28abd5138b48bb/html5/thumbnails/21.jpg)
Mycobacteria Growth Indicator
Tube (MGIT)
Tube contains modified Middlebrook 7H9
broth base with OADC enrichment amp
PANTA antibiotic mixture
All types of clinical specimens pulmonary
as well as extra-pulmonary ( except
blood) could be cultured on this type of
media
The MGIT 960 System
The MGIT 960 system is a non-radiometeric
automated system that uses the MGIT media amp
sensors to detect the fluorescence
Advantages
-The system holds 960 plastic tubes which are
continuously monitored
- Early detection as the machine monitoring amp
reading the tubes every hour
Detection and identification of mycobacteria directly
from clinical samplesbull Genotypic Methods
bull 1048708 PCR
bull 1048708 LAMP
bull 1048708 TMA NAA
bull 1048708 Ligase chain reaction
bull 1048708 Phenotypic Methods
bull 1048708 FAST Plaque TB
DrTVRao MD 23
bull Essentially PCR is a way to make millions of identical copies of a specific DNA sequence which may be a gene or a part of a gene or simply a stretch of nucleotides with a known DNA sequence the function of which may be unknown
Polymerase Chain Reaction (PCR)
DrTVRao MD 24
Polymerase Chain Reaction (PCR) amp
Gene probeNucleic acid probes amp nucleic acid amplification
tests in which polymerase enzymes are used to
amplify ( make many copies of specific DNA or
RNA sequences extracted from mycobacterial
cells
Advantages
- Rapid procedure - High sensitivity (1-10
( 3 ndash 4 hours) bacilli ml sputum)
bull Interferon-γ assays measure cell-mediated immunity by quantifying IFN-γ released from sensitized T cells in whole bloodPBMCs incubated with TB antigens
Quantiferon-GOLD
DrTVRao MD 26
What Positive Skin Test ( Tuberculin Test means)
bull A positive TB skin test or TB blood test only tells that a person has been infected with TB bacteria It does not tell whether the person has latent TB infection (LTBI) or has progressed to TB disease
DrTVRao MD 27
Tuberculin TestInterpretation A positive test indicates previous exposure and
carriage of TB A negative tuberculin test excludes infection in
suspected persons Tuberculin positive persons may develop
reactivation type of TB Tuberculin negative persons are at risk of gaining
new infection False positive reactions are mainly due to
- Infection with nontuberculous mycobacteria
DrTVRao MD 28
False negative reactions may be due to-
bull False negative reactions may be due to
- Sever tuberculosis infection (Miliary TB) -Hodgkinrsquos disease
bull Corticosteroid therapy - Malnutrition -AIDS
bull Children below 5 years of age with no exposure history
bull Positive test must be regarded suspicious
DrTVRao MD 29
Tuberculin Test( Mantoux Test )
bull Test to be interpreted in relation to clinical evaluation
bull Even the induration of 5 mm to be considered positive when tested on HIV patients
bull Lacks specificity
Positive Test Means
bull This means the personrsquos body was infected with TB bacteria Additional tests are needed to determine if the person has latent TB infection or TB disease A health care worker will then provide treatment as needed
DrTVRao MD 31
Negative Test Means
bull This means the personrsquos body did not react to the test and that latent TB infection or TB disease is not likely
DrTVRao MD 32
Tuberculin Testing - Limitations
bull False positive reactions are mainly due to
bull - Infection with nontuberculous mycobacteria
bull False negative reactions may be due to
bull - Sever tuberculosis infection (Miliary TB) -Hodgkinrsquos disease
bull - Corticosteroid therapy - Malnutrition -AIDS
bull Children below 5 years of age with no exposure history
bull - Positive test must be regarded suspicious DrTVRao MD 33
Recent Methods for Diagnosis
I ndash BACTEC 460 ( rapid radiometric culture system )
Specimens are cultured in a liquid medium (Middle brook7H9 broth base )containing C14 ndash labeled palmitic acid amp PANTA antibiotic mixture
Growing mycobacteria utilize the acid releasing radioactive CO2 which is measured as growth index (GI) in the BACTEC instrument
The daily increase in GI output is directly proportional to the rate amp amount of growth in the medium
DrTVRao MD 34
TB blood testsbull TB blood tests (also called interferon-gamma
release assays or IGRAs) measure how the immune system reacts to the bacteria that cause TB An IGRA measures how strong a personrsquos immune system reacts to TB bacteria by testing the personrsquos blood in a laboratory
bull Two IGRAs are approved by the US Food and Drug Administration (FDA) and are available in the United States
DrTVRao MD 35
Positive IGRAbull This means that the
person has been infected with TB bacteria Additional tests are needed to determine if the person has latent TB infection or TB disease A health care worker will then provide treatment as needed
DrTVRao MD 36
Negative IGRA
bull This means that the personrsquos blood did not react to the test and that latent TB infection or TB disease is not likely
DrTVRao MD 37
IGRAs are the preferred method of TB infection testing for the following
People who have received bacilli ChalmettendashGueacuterin (BCG) BCG is a vaccine for TB disease People who have a difficult time returning for a second appointment to look for a reaction to the TST
There is no problem with repeated IGRAs
DrTVRao MD 38
III Polymerase Chain Reaction
(PCR) amp Gene probeNucleic acid probes amp nucleic acid amplification
tests in which polymerase enzymes are used to
amplify ( make many copies of specific DNA or
RNA sequences extracted from mycobacterial
cells
Advantages
- Rapid procedure - High sensitivity (1-10
( 3 ndash 4 hours) bacilli ml sputum)
DrTVRao MD 39
Molecular DR testing is particularly useful for
bull Patients suspected or at high risk of having drug-resistant TBvery ill patients for whom drug-susceptibility information might alter case management decisions such as patients who do not get better while taking standard first-line therapy
DrTVRao MD 40
Detection of MDR Tuberculosis
bull Very ill patients for whom drug-susceptibility information might alter case management decisions such as patients who do not get better while taking standard first-line therapy
DrTVRao MD 41
Detection of MDR Tuberculosis
bull outbreak or contact investigations when drug resistance is suspected in the source case or in some severely immunocompromised persons such as HIV-infected persons or those receiving dialysis in which knowledge of drug-susceptibility would be a significant benefit and affect preventive therapy decisions
DrTVRao MD 42
Tuberculosis and HIV infection
bull HIV association has become a threat to the developed countries too
bull HIV association will lead to rapid spread of tuberculosis
DrTVRao MD 43
HIV Considerations
bull HIV is the strongest risk factor for progression to active disease
bull HIV kills CD4+ T Helper cells which normally inhibit M tuberculosis
bull HIV interferes with PPD skin test
bull Protease inhibitors interfere with rifampin
DrTVRao MD 44
Epidemiologybull An ancient disease called as white plague
bull 13 of the world population is infected
bull 2 billion infected
bull Each year 9 lakhs to 1 million are infected
bull Poor nations phase the burnt of the disease
bull In developing world gt 4o of the population is effected
bull 15 million suffer the disease
bull 3 million are highly infective
DrTVRao MD 45
MDR tuberculosis
bull Multidrug resistant tuberculosis has become a global threat
bull In 1993 WHO declared Tuberculosis a Global emergency
bull Animals shed the bacilli in Milk humanrsquos get infected after drinking the unsterilized Milk
bull Pasteurization has reduced the incidence of Bovine tuberculosis
DrTVRao MD 46
Why Tuberculosis continues to be Important
bull Someone in the world is newly infected with TB bacilli every second
bull Overall one-third of the worlds population is currently infected with the TB bacillus
bull 5-10 of people who are infected with TB bacilli (but who are not infected with HIV) become sick or infectious at some time during their life People with HIV and TB infection are much more likely to develop TB
DrTVRao MD 47
bull Programme Created by DrTVRao MD for Medical and Paramedical
Students in Developing world
bull Email
bull doctortvraogmailcom
DrTVRao MD 48
![Page 22: Diagnosis of tuberculosis an Update](https://reader031.fdocuments.in/reader031/viewer/2022032113/55a62b711a28abd5138b48bb/html5/thumbnails/22.jpg)
The MGIT 960 System
The MGIT 960 system is a non-radiometeric
automated system that uses the MGIT media amp
sensors to detect the fluorescence
Advantages
-The system holds 960 plastic tubes which are
continuously monitored
- Early detection as the machine monitoring amp
reading the tubes every hour
Detection and identification of mycobacteria directly
from clinical samplesbull Genotypic Methods
bull 1048708 PCR
bull 1048708 LAMP
bull 1048708 TMA NAA
bull 1048708 Ligase chain reaction
bull 1048708 Phenotypic Methods
bull 1048708 FAST Plaque TB
DrTVRao MD 23
bull Essentially PCR is a way to make millions of identical copies of a specific DNA sequence which may be a gene or a part of a gene or simply a stretch of nucleotides with a known DNA sequence the function of which may be unknown
Polymerase Chain Reaction (PCR)
DrTVRao MD 24
Polymerase Chain Reaction (PCR) amp
Gene probeNucleic acid probes amp nucleic acid amplification
tests in which polymerase enzymes are used to
amplify ( make many copies of specific DNA or
RNA sequences extracted from mycobacterial
cells
Advantages
- Rapid procedure - High sensitivity (1-10
( 3 ndash 4 hours) bacilli ml sputum)
bull Interferon-γ assays measure cell-mediated immunity by quantifying IFN-γ released from sensitized T cells in whole bloodPBMCs incubated with TB antigens
Quantiferon-GOLD
DrTVRao MD 26
What Positive Skin Test ( Tuberculin Test means)
bull A positive TB skin test or TB blood test only tells that a person has been infected with TB bacteria It does not tell whether the person has latent TB infection (LTBI) or has progressed to TB disease
DrTVRao MD 27
Tuberculin TestInterpretation A positive test indicates previous exposure and
carriage of TB A negative tuberculin test excludes infection in
suspected persons Tuberculin positive persons may develop
reactivation type of TB Tuberculin negative persons are at risk of gaining
new infection False positive reactions are mainly due to
- Infection with nontuberculous mycobacteria
DrTVRao MD 28
False negative reactions may be due to-
bull False negative reactions may be due to
- Sever tuberculosis infection (Miliary TB) -Hodgkinrsquos disease
bull Corticosteroid therapy - Malnutrition -AIDS
bull Children below 5 years of age with no exposure history
bull Positive test must be regarded suspicious
DrTVRao MD 29
Tuberculin Test( Mantoux Test )
bull Test to be interpreted in relation to clinical evaluation
bull Even the induration of 5 mm to be considered positive when tested on HIV patients
bull Lacks specificity
Positive Test Means
bull This means the personrsquos body was infected with TB bacteria Additional tests are needed to determine if the person has latent TB infection or TB disease A health care worker will then provide treatment as needed
DrTVRao MD 31
Negative Test Means
bull This means the personrsquos body did not react to the test and that latent TB infection or TB disease is not likely
DrTVRao MD 32
Tuberculin Testing - Limitations
bull False positive reactions are mainly due to
bull - Infection with nontuberculous mycobacteria
bull False negative reactions may be due to
bull - Sever tuberculosis infection (Miliary TB) -Hodgkinrsquos disease
bull - Corticosteroid therapy - Malnutrition -AIDS
bull Children below 5 years of age with no exposure history
bull - Positive test must be regarded suspicious DrTVRao MD 33
Recent Methods for Diagnosis
I ndash BACTEC 460 ( rapid radiometric culture system )
Specimens are cultured in a liquid medium (Middle brook7H9 broth base )containing C14 ndash labeled palmitic acid amp PANTA antibiotic mixture
Growing mycobacteria utilize the acid releasing radioactive CO2 which is measured as growth index (GI) in the BACTEC instrument
The daily increase in GI output is directly proportional to the rate amp amount of growth in the medium
DrTVRao MD 34
TB blood testsbull TB blood tests (also called interferon-gamma
release assays or IGRAs) measure how the immune system reacts to the bacteria that cause TB An IGRA measures how strong a personrsquos immune system reacts to TB bacteria by testing the personrsquos blood in a laboratory
bull Two IGRAs are approved by the US Food and Drug Administration (FDA) and are available in the United States
DrTVRao MD 35
Positive IGRAbull This means that the
person has been infected with TB bacteria Additional tests are needed to determine if the person has latent TB infection or TB disease A health care worker will then provide treatment as needed
DrTVRao MD 36
Negative IGRA
bull This means that the personrsquos blood did not react to the test and that latent TB infection or TB disease is not likely
DrTVRao MD 37
IGRAs are the preferred method of TB infection testing for the following
People who have received bacilli ChalmettendashGueacuterin (BCG) BCG is a vaccine for TB disease People who have a difficult time returning for a second appointment to look for a reaction to the TST
There is no problem with repeated IGRAs
DrTVRao MD 38
III Polymerase Chain Reaction
(PCR) amp Gene probeNucleic acid probes amp nucleic acid amplification
tests in which polymerase enzymes are used to
amplify ( make many copies of specific DNA or
RNA sequences extracted from mycobacterial
cells
Advantages
- Rapid procedure - High sensitivity (1-10
( 3 ndash 4 hours) bacilli ml sputum)
DrTVRao MD 39
Molecular DR testing is particularly useful for
bull Patients suspected or at high risk of having drug-resistant TBvery ill patients for whom drug-susceptibility information might alter case management decisions such as patients who do not get better while taking standard first-line therapy
DrTVRao MD 40
Detection of MDR Tuberculosis
bull Very ill patients for whom drug-susceptibility information might alter case management decisions such as patients who do not get better while taking standard first-line therapy
DrTVRao MD 41
Detection of MDR Tuberculosis
bull outbreak or contact investigations when drug resistance is suspected in the source case or in some severely immunocompromised persons such as HIV-infected persons or those receiving dialysis in which knowledge of drug-susceptibility would be a significant benefit and affect preventive therapy decisions
DrTVRao MD 42
Tuberculosis and HIV infection
bull HIV association has become a threat to the developed countries too
bull HIV association will lead to rapid spread of tuberculosis
DrTVRao MD 43
HIV Considerations
bull HIV is the strongest risk factor for progression to active disease
bull HIV kills CD4+ T Helper cells which normally inhibit M tuberculosis
bull HIV interferes with PPD skin test
bull Protease inhibitors interfere with rifampin
DrTVRao MD 44
Epidemiologybull An ancient disease called as white plague
bull 13 of the world population is infected
bull 2 billion infected
bull Each year 9 lakhs to 1 million are infected
bull Poor nations phase the burnt of the disease
bull In developing world gt 4o of the population is effected
bull 15 million suffer the disease
bull 3 million are highly infective
DrTVRao MD 45
MDR tuberculosis
bull Multidrug resistant tuberculosis has become a global threat
bull In 1993 WHO declared Tuberculosis a Global emergency
bull Animals shed the bacilli in Milk humanrsquos get infected after drinking the unsterilized Milk
bull Pasteurization has reduced the incidence of Bovine tuberculosis
DrTVRao MD 46
Why Tuberculosis continues to be Important
bull Someone in the world is newly infected with TB bacilli every second
bull Overall one-third of the worlds population is currently infected with the TB bacillus
bull 5-10 of people who are infected with TB bacilli (but who are not infected with HIV) become sick or infectious at some time during their life People with HIV and TB infection are much more likely to develop TB
DrTVRao MD 47
bull Programme Created by DrTVRao MD for Medical and Paramedical
Students in Developing world
bull Email
bull doctortvraogmailcom
DrTVRao MD 48
![Page 23: Diagnosis of tuberculosis an Update](https://reader031.fdocuments.in/reader031/viewer/2022032113/55a62b711a28abd5138b48bb/html5/thumbnails/23.jpg)
Detection and identification of mycobacteria directly
from clinical samplesbull Genotypic Methods
bull 1048708 PCR
bull 1048708 LAMP
bull 1048708 TMA NAA
bull 1048708 Ligase chain reaction
bull 1048708 Phenotypic Methods
bull 1048708 FAST Plaque TB
DrTVRao MD 23
bull Essentially PCR is a way to make millions of identical copies of a specific DNA sequence which may be a gene or a part of a gene or simply a stretch of nucleotides with a known DNA sequence the function of which may be unknown
Polymerase Chain Reaction (PCR)
DrTVRao MD 24
Polymerase Chain Reaction (PCR) amp
Gene probeNucleic acid probes amp nucleic acid amplification
tests in which polymerase enzymes are used to
amplify ( make many copies of specific DNA or
RNA sequences extracted from mycobacterial
cells
Advantages
- Rapid procedure - High sensitivity (1-10
( 3 ndash 4 hours) bacilli ml sputum)
bull Interferon-γ assays measure cell-mediated immunity by quantifying IFN-γ released from sensitized T cells in whole bloodPBMCs incubated with TB antigens
Quantiferon-GOLD
DrTVRao MD 26
What Positive Skin Test ( Tuberculin Test means)
bull A positive TB skin test or TB blood test only tells that a person has been infected with TB bacteria It does not tell whether the person has latent TB infection (LTBI) or has progressed to TB disease
DrTVRao MD 27
Tuberculin TestInterpretation A positive test indicates previous exposure and
carriage of TB A negative tuberculin test excludes infection in
suspected persons Tuberculin positive persons may develop
reactivation type of TB Tuberculin negative persons are at risk of gaining
new infection False positive reactions are mainly due to
- Infection with nontuberculous mycobacteria
DrTVRao MD 28
False negative reactions may be due to-
bull False negative reactions may be due to
- Sever tuberculosis infection (Miliary TB) -Hodgkinrsquos disease
bull Corticosteroid therapy - Malnutrition -AIDS
bull Children below 5 years of age with no exposure history
bull Positive test must be regarded suspicious
DrTVRao MD 29
Tuberculin Test( Mantoux Test )
bull Test to be interpreted in relation to clinical evaluation
bull Even the induration of 5 mm to be considered positive when tested on HIV patients
bull Lacks specificity
Positive Test Means
bull This means the personrsquos body was infected with TB bacteria Additional tests are needed to determine if the person has latent TB infection or TB disease A health care worker will then provide treatment as needed
DrTVRao MD 31
Negative Test Means
bull This means the personrsquos body did not react to the test and that latent TB infection or TB disease is not likely
DrTVRao MD 32
Tuberculin Testing - Limitations
bull False positive reactions are mainly due to
bull - Infection with nontuberculous mycobacteria
bull False negative reactions may be due to
bull - Sever tuberculosis infection (Miliary TB) -Hodgkinrsquos disease
bull - Corticosteroid therapy - Malnutrition -AIDS
bull Children below 5 years of age with no exposure history
bull - Positive test must be regarded suspicious DrTVRao MD 33
Recent Methods for Diagnosis
I ndash BACTEC 460 ( rapid radiometric culture system )
Specimens are cultured in a liquid medium (Middle brook7H9 broth base )containing C14 ndash labeled palmitic acid amp PANTA antibiotic mixture
Growing mycobacteria utilize the acid releasing radioactive CO2 which is measured as growth index (GI) in the BACTEC instrument
The daily increase in GI output is directly proportional to the rate amp amount of growth in the medium
DrTVRao MD 34
TB blood testsbull TB blood tests (also called interferon-gamma
release assays or IGRAs) measure how the immune system reacts to the bacteria that cause TB An IGRA measures how strong a personrsquos immune system reacts to TB bacteria by testing the personrsquos blood in a laboratory
bull Two IGRAs are approved by the US Food and Drug Administration (FDA) and are available in the United States
DrTVRao MD 35
Positive IGRAbull This means that the
person has been infected with TB bacteria Additional tests are needed to determine if the person has latent TB infection or TB disease A health care worker will then provide treatment as needed
DrTVRao MD 36
Negative IGRA
bull This means that the personrsquos blood did not react to the test and that latent TB infection or TB disease is not likely
DrTVRao MD 37
IGRAs are the preferred method of TB infection testing for the following
People who have received bacilli ChalmettendashGueacuterin (BCG) BCG is a vaccine for TB disease People who have a difficult time returning for a second appointment to look for a reaction to the TST
There is no problem with repeated IGRAs
DrTVRao MD 38
III Polymerase Chain Reaction
(PCR) amp Gene probeNucleic acid probes amp nucleic acid amplification
tests in which polymerase enzymes are used to
amplify ( make many copies of specific DNA or
RNA sequences extracted from mycobacterial
cells
Advantages
- Rapid procedure - High sensitivity (1-10
( 3 ndash 4 hours) bacilli ml sputum)
DrTVRao MD 39
Molecular DR testing is particularly useful for
bull Patients suspected or at high risk of having drug-resistant TBvery ill patients for whom drug-susceptibility information might alter case management decisions such as patients who do not get better while taking standard first-line therapy
DrTVRao MD 40
Detection of MDR Tuberculosis
bull Very ill patients for whom drug-susceptibility information might alter case management decisions such as patients who do not get better while taking standard first-line therapy
DrTVRao MD 41
Detection of MDR Tuberculosis
bull outbreak or contact investigations when drug resistance is suspected in the source case or in some severely immunocompromised persons such as HIV-infected persons or those receiving dialysis in which knowledge of drug-susceptibility would be a significant benefit and affect preventive therapy decisions
DrTVRao MD 42
Tuberculosis and HIV infection
bull HIV association has become a threat to the developed countries too
bull HIV association will lead to rapid spread of tuberculosis
DrTVRao MD 43
HIV Considerations
bull HIV is the strongest risk factor for progression to active disease
bull HIV kills CD4+ T Helper cells which normally inhibit M tuberculosis
bull HIV interferes with PPD skin test
bull Protease inhibitors interfere with rifampin
DrTVRao MD 44
Epidemiologybull An ancient disease called as white plague
bull 13 of the world population is infected
bull 2 billion infected
bull Each year 9 lakhs to 1 million are infected
bull Poor nations phase the burnt of the disease
bull In developing world gt 4o of the population is effected
bull 15 million suffer the disease
bull 3 million are highly infective
DrTVRao MD 45
MDR tuberculosis
bull Multidrug resistant tuberculosis has become a global threat
bull In 1993 WHO declared Tuberculosis a Global emergency
bull Animals shed the bacilli in Milk humanrsquos get infected after drinking the unsterilized Milk
bull Pasteurization has reduced the incidence of Bovine tuberculosis
DrTVRao MD 46
Why Tuberculosis continues to be Important
bull Someone in the world is newly infected with TB bacilli every second
bull Overall one-third of the worlds population is currently infected with the TB bacillus
bull 5-10 of people who are infected with TB bacilli (but who are not infected with HIV) become sick or infectious at some time during their life People with HIV and TB infection are much more likely to develop TB
DrTVRao MD 47
bull Programme Created by DrTVRao MD for Medical and Paramedical
Students in Developing world
bull Email
bull doctortvraogmailcom
DrTVRao MD 48
![Page 24: Diagnosis of tuberculosis an Update](https://reader031.fdocuments.in/reader031/viewer/2022032113/55a62b711a28abd5138b48bb/html5/thumbnails/24.jpg)
bull Essentially PCR is a way to make millions of identical copies of a specific DNA sequence which may be a gene or a part of a gene or simply a stretch of nucleotides with a known DNA sequence the function of which may be unknown
Polymerase Chain Reaction (PCR)
DrTVRao MD 24
Polymerase Chain Reaction (PCR) amp
Gene probeNucleic acid probes amp nucleic acid amplification
tests in which polymerase enzymes are used to
amplify ( make many copies of specific DNA or
RNA sequences extracted from mycobacterial
cells
Advantages
- Rapid procedure - High sensitivity (1-10
( 3 ndash 4 hours) bacilli ml sputum)
bull Interferon-γ assays measure cell-mediated immunity by quantifying IFN-γ released from sensitized T cells in whole bloodPBMCs incubated with TB antigens
Quantiferon-GOLD
DrTVRao MD 26
What Positive Skin Test ( Tuberculin Test means)
bull A positive TB skin test or TB blood test only tells that a person has been infected with TB bacteria It does not tell whether the person has latent TB infection (LTBI) or has progressed to TB disease
DrTVRao MD 27
Tuberculin TestInterpretation A positive test indicates previous exposure and
carriage of TB A negative tuberculin test excludes infection in
suspected persons Tuberculin positive persons may develop
reactivation type of TB Tuberculin negative persons are at risk of gaining
new infection False positive reactions are mainly due to
- Infection with nontuberculous mycobacteria
DrTVRao MD 28
False negative reactions may be due to-
bull False negative reactions may be due to
- Sever tuberculosis infection (Miliary TB) -Hodgkinrsquos disease
bull Corticosteroid therapy - Malnutrition -AIDS
bull Children below 5 years of age with no exposure history
bull Positive test must be regarded suspicious
DrTVRao MD 29
Tuberculin Test( Mantoux Test )
bull Test to be interpreted in relation to clinical evaluation
bull Even the induration of 5 mm to be considered positive when tested on HIV patients
bull Lacks specificity
Positive Test Means
bull This means the personrsquos body was infected with TB bacteria Additional tests are needed to determine if the person has latent TB infection or TB disease A health care worker will then provide treatment as needed
DrTVRao MD 31
Negative Test Means
bull This means the personrsquos body did not react to the test and that latent TB infection or TB disease is not likely
DrTVRao MD 32
Tuberculin Testing - Limitations
bull False positive reactions are mainly due to
bull - Infection with nontuberculous mycobacteria
bull False negative reactions may be due to
bull - Sever tuberculosis infection (Miliary TB) -Hodgkinrsquos disease
bull - Corticosteroid therapy - Malnutrition -AIDS
bull Children below 5 years of age with no exposure history
bull - Positive test must be regarded suspicious DrTVRao MD 33
Recent Methods for Diagnosis
I ndash BACTEC 460 ( rapid radiometric culture system )
Specimens are cultured in a liquid medium (Middle brook7H9 broth base )containing C14 ndash labeled palmitic acid amp PANTA antibiotic mixture
Growing mycobacteria utilize the acid releasing radioactive CO2 which is measured as growth index (GI) in the BACTEC instrument
The daily increase in GI output is directly proportional to the rate amp amount of growth in the medium
DrTVRao MD 34
TB blood testsbull TB blood tests (also called interferon-gamma
release assays or IGRAs) measure how the immune system reacts to the bacteria that cause TB An IGRA measures how strong a personrsquos immune system reacts to TB bacteria by testing the personrsquos blood in a laboratory
bull Two IGRAs are approved by the US Food and Drug Administration (FDA) and are available in the United States
DrTVRao MD 35
Positive IGRAbull This means that the
person has been infected with TB bacteria Additional tests are needed to determine if the person has latent TB infection or TB disease A health care worker will then provide treatment as needed
DrTVRao MD 36
Negative IGRA
bull This means that the personrsquos blood did not react to the test and that latent TB infection or TB disease is not likely
DrTVRao MD 37
IGRAs are the preferred method of TB infection testing for the following
People who have received bacilli ChalmettendashGueacuterin (BCG) BCG is a vaccine for TB disease People who have a difficult time returning for a second appointment to look for a reaction to the TST
There is no problem with repeated IGRAs
DrTVRao MD 38
III Polymerase Chain Reaction
(PCR) amp Gene probeNucleic acid probes amp nucleic acid amplification
tests in which polymerase enzymes are used to
amplify ( make many copies of specific DNA or
RNA sequences extracted from mycobacterial
cells
Advantages
- Rapid procedure - High sensitivity (1-10
( 3 ndash 4 hours) bacilli ml sputum)
DrTVRao MD 39
Molecular DR testing is particularly useful for
bull Patients suspected or at high risk of having drug-resistant TBvery ill patients for whom drug-susceptibility information might alter case management decisions such as patients who do not get better while taking standard first-line therapy
DrTVRao MD 40
Detection of MDR Tuberculosis
bull Very ill patients for whom drug-susceptibility information might alter case management decisions such as patients who do not get better while taking standard first-line therapy
DrTVRao MD 41
Detection of MDR Tuberculosis
bull outbreak or contact investigations when drug resistance is suspected in the source case or in some severely immunocompromised persons such as HIV-infected persons or those receiving dialysis in which knowledge of drug-susceptibility would be a significant benefit and affect preventive therapy decisions
DrTVRao MD 42
Tuberculosis and HIV infection
bull HIV association has become a threat to the developed countries too
bull HIV association will lead to rapid spread of tuberculosis
DrTVRao MD 43
HIV Considerations
bull HIV is the strongest risk factor for progression to active disease
bull HIV kills CD4+ T Helper cells which normally inhibit M tuberculosis
bull HIV interferes with PPD skin test
bull Protease inhibitors interfere with rifampin
DrTVRao MD 44
Epidemiologybull An ancient disease called as white plague
bull 13 of the world population is infected
bull 2 billion infected
bull Each year 9 lakhs to 1 million are infected
bull Poor nations phase the burnt of the disease
bull In developing world gt 4o of the population is effected
bull 15 million suffer the disease
bull 3 million are highly infective
DrTVRao MD 45
MDR tuberculosis
bull Multidrug resistant tuberculosis has become a global threat
bull In 1993 WHO declared Tuberculosis a Global emergency
bull Animals shed the bacilli in Milk humanrsquos get infected after drinking the unsterilized Milk
bull Pasteurization has reduced the incidence of Bovine tuberculosis
DrTVRao MD 46
Why Tuberculosis continues to be Important
bull Someone in the world is newly infected with TB bacilli every second
bull Overall one-third of the worlds population is currently infected with the TB bacillus
bull 5-10 of people who are infected with TB bacilli (but who are not infected with HIV) become sick or infectious at some time during their life People with HIV and TB infection are much more likely to develop TB
DrTVRao MD 47
bull Programme Created by DrTVRao MD for Medical and Paramedical
Students in Developing world
bull Email
bull doctortvraogmailcom
DrTVRao MD 48
![Page 25: Diagnosis of tuberculosis an Update](https://reader031.fdocuments.in/reader031/viewer/2022032113/55a62b711a28abd5138b48bb/html5/thumbnails/25.jpg)
Polymerase Chain Reaction (PCR) amp
Gene probeNucleic acid probes amp nucleic acid amplification
tests in which polymerase enzymes are used to
amplify ( make many copies of specific DNA or
RNA sequences extracted from mycobacterial
cells
Advantages
- Rapid procedure - High sensitivity (1-10
( 3 ndash 4 hours) bacilli ml sputum)
bull Interferon-γ assays measure cell-mediated immunity by quantifying IFN-γ released from sensitized T cells in whole bloodPBMCs incubated with TB antigens
Quantiferon-GOLD
DrTVRao MD 26
What Positive Skin Test ( Tuberculin Test means)
bull A positive TB skin test or TB blood test only tells that a person has been infected with TB bacteria It does not tell whether the person has latent TB infection (LTBI) or has progressed to TB disease
DrTVRao MD 27
Tuberculin TestInterpretation A positive test indicates previous exposure and
carriage of TB A negative tuberculin test excludes infection in
suspected persons Tuberculin positive persons may develop
reactivation type of TB Tuberculin negative persons are at risk of gaining
new infection False positive reactions are mainly due to
- Infection with nontuberculous mycobacteria
DrTVRao MD 28
False negative reactions may be due to-
bull False negative reactions may be due to
- Sever tuberculosis infection (Miliary TB) -Hodgkinrsquos disease
bull Corticosteroid therapy - Malnutrition -AIDS
bull Children below 5 years of age with no exposure history
bull Positive test must be regarded suspicious
DrTVRao MD 29
Tuberculin Test( Mantoux Test )
bull Test to be interpreted in relation to clinical evaluation
bull Even the induration of 5 mm to be considered positive when tested on HIV patients
bull Lacks specificity
Positive Test Means
bull This means the personrsquos body was infected with TB bacteria Additional tests are needed to determine if the person has latent TB infection or TB disease A health care worker will then provide treatment as needed
DrTVRao MD 31
Negative Test Means
bull This means the personrsquos body did not react to the test and that latent TB infection or TB disease is not likely
DrTVRao MD 32
Tuberculin Testing - Limitations
bull False positive reactions are mainly due to
bull - Infection with nontuberculous mycobacteria
bull False negative reactions may be due to
bull - Sever tuberculosis infection (Miliary TB) -Hodgkinrsquos disease
bull - Corticosteroid therapy - Malnutrition -AIDS
bull Children below 5 years of age with no exposure history
bull - Positive test must be regarded suspicious DrTVRao MD 33
Recent Methods for Diagnosis
I ndash BACTEC 460 ( rapid radiometric culture system )
Specimens are cultured in a liquid medium (Middle brook7H9 broth base )containing C14 ndash labeled palmitic acid amp PANTA antibiotic mixture
Growing mycobacteria utilize the acid releasing radioactive CO2 which is measured as growth index (GI) in the BACTEC instrument
The daily increase in GI output is directly proportional to the rate amp amount of growth in the medium
DrTVRao MD 34
TB blood testsbull TB blood tests (also called interferon-gamma
release assays or IGRAs) measure how the immune system reacts to the bacteria that cause TB An IGRA measures how strong a personrsquos immune system reacts to TB bacteria by testing the personrsquos blood in a laboratory
bull Two IGRAs are approved by the US Food and Drug Administration (FDA) and are available in the United States
DrTVRao MD 35
Positive IGRAbull This means that the
person has been infected with TB bacteria Additional tests are needed to determine if the person has latent TB infection or TB disease A health care worker will then provide treatment as needed
DrTVRao MD 36
Negative IGRA
bull This means that the personrsquos blood did not react to the test and that latent TB infection or TB disease is not likely
DrTVRao MD 37
IGRAs are the preferred method of TB infection testing for the following
People who have received bacilli ChalmettendashGueacuterin (BCG) BCG is a vaccine for TB disease People who have a difficult time returning for a second appointment to look for a reaction to the TST
There is no problem with repeated IGRAs
DrTVRao MD 38
III Polymerase Chain Reaction
(PCR) amp Gene probeNucleic acid probes amp nucleic acid amplification
tests in which polymerase enzymes are used to
amplify ( make many copies of specific DNA or
RNA sequences extracted from mycobacterial
cells
Advantages
- Rapid procedure - High sensitivity (1-10
( 3 ndash 4 hours) bacilli ml sputum)
DrTVRao MD 39
Molecular DR testing is particularly useful for
bull Patients suspected or at high risk of having drug-resistant TBvery ill patients for whom drug-susceptibility information might alter case management decisions such as patients who do not get better while taking standard first-line therapy
DrTVRao MD 40
Detection of MDR Tuberculosis
bull Very ill patients for whom drug-susceptibility information might alter case management decisions such as patients who do not get better while taking standard first-line therapy
DrTVRao MD 41
Detection of MDR Tuberculosis
bull outbreak or contact investigations when drug resistance is suspected in the source case or in some severely immunocompromised persons such as HIV-infected persons or those receiving dialysis in which knowledge of drug-susceptibility would be a significant benefit and affect preventive therapy decisions
DrTVRao MD 42
Tuberculosis and HIV infection
bull HIV association has become a threat to the developed countries too
bull HIV association will lead to rapid spread of tuberculosis
DrTVRao MD 43
HIV Considerations
bull HIV is the strongest risk factor for progression to active disease
bull HIV kills CD4+ T Helper cells which normally inhibit M tuberculosis
bull HIV interferes with PPD skin test
bull Protease inhibitors interfere with rifampin
DrTVRao MD 44
Epidemiologybull An ancient disease called as white plague
bull 13 of the world population is infected
bull 2 billion infected
bull Each year 9 lakhs to 1 million are infected
bull Poor nations phase the burnt of the disease
bull In developing world gt 4o of the population is effected
bull 15 million suffer the disease
bull 3 million are highly infective
DrTVRao MD 45
MDR tuberculosis
bull Multidrug resistant tuberculosis has become a global threat
bull In 1993 WHO declared Tuberculosis a Global emergency
bull Animals shed the bacilli in Milk humanrsquos get infected after drinking the unsterilized Milk
bull Pasteurization has reduced the incidence of Bovine tuberculosis
DrTVRao MD 46
Why Tuberculosis continues to be Important
bull Someone in the world is newly infected with TB bacilli every second
bull Overall one-third of the worlds population is currently infected with the TB bacillus
bull 5-10 of people who are infected with TB bacilli (but who are not infected with HIV) become sick or infectious at some time during their life People with HIV and TB infection are much more likely to develop TB
DrTVRao MD 47
bull Programme Created by DrTVRao MD for Medical and Paramedical
Students in Developing world
bull Email
bull doctortvraogmailcom
DrTVRao MD 48
![Page 26: Diagnosis of tuberculosis an Update](https://reader031.fdocuments.in/reader031/viewer/2022032113/55a62b711a28abd5138b48bb/html5/thumbnails/26.jpg)
bull Interferon-γ assays measure cell-mediated immunity by quantifying IFN-γ released from sensitized T cells in whole bloodPBMCs incubated with TB antigens
Quantiferon-GOLD
DrTVRao MD 26
What Positive Skin Test ( Tuberculin Test means)
bull A positive TB skin test or TB blood test only tells that a person has been infected with TB bacteria It does not tell whether the person has latent TB infection (LTBI) or has progressed to TB disease
DrTVRao MD 27
Tuberculin TestInterpretation A positive test indicates previous exposure and
carriage of TB A negative tuberculin test excludes infection in
suspected persons Tuberculin positive persons may develop
reactivation type of TB Tuberculin negative persons are at risk of gaining
new infection False positive reactions are mainly due to
- Infection with nontuberculous mycobacteria
DrTVRao MD 28
False negative reactions may be due to-
bull False negative reactions may be due to
- Sever tuberculosis infection (Miliary TB) -Hodgkinrsquos disease
bull Corticosteroid therapy - Malnutrition -AIDS
bull Children below 5 years of age with no exposure history
bull Positive test must be regarded suspicious
DrTVRao MD 29
Tuberculin Test( Mantoux Test )
bull Test to be interpreted in relation to clinical evaluation
bull Even the induration of 5 mm to be considered positive when tested on HIV patients
bull Lacks specificity
Positive Test Means
bull This means the personrsquos body was infected with TB bacteria Additional tests are needed to determine if the person has latent TB infection or TB disease A health care worker will then provide treatment as needed
DrTVRao MD 31
Negative Test Means
bull This means the personrsquos body did not react to the test and that latent TB infection or TB disease is not likely
DrTVRao MD 32
Tuberculin Testing - Limitations
bull False positive reactions are mainly due to
bull - Infection with nontuberculous mycobacteria
bull False negative reactions may be due to
bull - Sever tuberculosis infection (Miliary TB) -Hodgkinrsquos disease
bull - Corticosteroid therapy - Malnutrition -AIDS
bull Children below 5 years of age with no exposure history
bull - Positive test must be regarded suspicious DrTVRao MD 33
Recent Methods for Diagnosis
I ndash BACTEC 460 ( rapid radiometric culture system )
Specimens are cultured in a liquid medium (Middle brook7H9 broth base )containing C14 ndash labeled palmitic acid amp PANTA antibiotic mixture
Growing mycobacteria utilize the acid releasing radioactive CO2 which is measured as growth index (GI) in the BACTEC instrument
The daily increase in GI output is directly proportional to the rate amp amount of growth in the medium
DrTVRao MD 34
TB blood testsbull TB blood tests (also called interferon-gamma
release assays or IGRAs) measure how the immune system reacts to the bacteria that cause TB An IGRA measures how strong a personrsquos immune system reacts to TB bacteria by testing the personrsquos blood in a laboratory
bull Two IGRAs are approved by the US Food and Drug Administration (FDA) and are available in the United States
DrTVRao MD 35
Positive IGRAbull This means that the
person has been infected with TB bacteria Additional tests are needed to determine if the person has latent TB infection or TB disease A health care worker will then provide treatment as needed
DrTVRao MD 36
Negative IGRA
bull This means that the personrsquos blood did not react to the test and that latent TB infection or TB disease is not likely
DrTVRao MD 37
IGRAs are the preferred method of TB infection testing for the following
People who have received bacilli ChalmettendashGueacuterin (BCG) BCG is a vaccine for TB disease People who have a difficult time returning for a second appointment to look for a reaction to the TST
There is no problem with repeated IGRAs
DrTVRao MD 38
III Polymerase Chain Reaction
(PCR) amp Gene probeNucleic acid probes amp nucleic acid amplification
tests in which polymerase enzymes are used to
amplify ( make many copies of specific DNA or
RNA sequences extracted from mycobacterial
cells
Advantages
- Rapid procedure - High sensitivity (1-10
( 3 ndash 4 hours) bacilli ml sputum)
DrTVRao MD 39
Molecular DR testing is particularly useful for
bull Patients suspected or at high risk of having drug-resistant TBvery ill patients for whom drug-susceptibility information might alter case management decisions such as patients who do not get better while taking standard first-line therapy
DrTVRao MD 40
Detection of MDR Tuberculosis
bull Very ill patients for whom drug-susceptibility information might alter case management decisions such as patients who do not get better while taking standard first-line therapy
DrTVRao MD 41
Detection of MDR Tuberculosis
bull outbreak or contact investigations when drug resistance is suspected in the source case or in some severely immunocompromised persons such as HIV-infected persons or those receiving dialysis in which knowledge of drug-susceptibility would be a significant benefit and affect preventive therapy decisions
DrTVRao MD 42
Tuberculosis and HIV infection
bull HIV association has become a threat to the developed countries too
bull HIV association will lead to rapid spread of tuberculosis
DrTVRao MD 43
HIV Considerations
bull HIV is the strongest risk factor for progression to active disease
bull HIV kills CD4+ T Helper cells which normally inhibit M tuberculosis
bull HIV interferes with PPD skin test
bull Protease inhibitors interfere with rifampin
DrTVRao MD 44
Epidemiologybull An ancient disease called as white plague
bull 13 of the world population is infected
bull 2 billion infected
bull Each year 9 lakhs to 1 million are infected
bull Poor nations phase the burnt of the disease
bull In developing world gt 4o of the population is effected
bull 15 million suffer the disease
bull 3 million are highly infective
DrTVRao MD 45
MDR tuberculosis
bull Multidrug resistant tuberculosis has become a global threat
bull In 1993 WHO declared Tuberculosis a Global emergency
bull Animals shed the bacilli in Milk humanrsquos get infected after drinking the unsterilized Milk
bull Pasteurization has reduced the incidence of Bovine tuberculosis
DrTVRao MD 46
Why Tuberculosis continues to be Important
bull Someone in the world is newly infected with TB bacilli every second
bull Overall one-third of the worlds population is currently infected with the TB bacillus
bull 5-10 of people who are infected with TB bacilli (but who are not infected with HIV) become sick or infectious at some time during their life People with HIV and TB infection are much more likely to develop TB
DrTVRao MD 47
bull Programme Created by DrTVRao MD for Medical and Paramedical
Students in Developing world
bull Email
bull doctortvraogmailcom
DrTVRao MD 48
![Page 27: Diagnosis of tuberculosis an Update](https://reader031.fdocuments.in/reader031/viewer/2022032113/55a62b711a28abd5138b48bb/html5/thumbnails/27.jpg)
What Positive Skin Test ( Tuberculin Test means)
bull A positive TB skin test or TB blood test only tells that a person has been infected with TB bacteria It does not tell whether the person has latent TB infection (LTBI) or has progressed to TB disease
DrTVRao MD 27
Tuberculin TestInterpretation A positive test indicates previous exposure and
carriage of TB A negative tuberculin test excludes infection in
suspected persons Tuberculin positive persons may develop
reactivation type of TB Tuberculin negative persons are at risk of gaining
new infection False positive reactions are mainly due to
- Infection with nontuberculous mycobacteria
DrTVRao MD 28
False negative reactions may be due to-
bull False negative reactions may be due to
- Sever tuberculosis infection (Miliary TB) -Hodgkinrsquos disease
bull Corticosteroid therapy - Malnutrition -AIDS
bull Children below 5 years of age with no exposure history
bull Positive test must be regarded suspicious
DrTVRao MD 29
Tuberculin Test( Mantoux Test )
bull Test to be interpreted in relation to clinical evaluation
bull Even the induration of 5 mm to be considered positive when tested on HIV patients
bull Lacks specificity
Positive Test Means
bull This means the personrsquos body was infected with TB bacteria Additional tests are needed to determine if the person has latent TB infection or TB disease A health care worker will then provide treatment as needed
DrTVRao MD 31
Negative Test Means
bull This means the personrsquos body did not react to the test and that latent TB infection or TB disease is not likely
DrTVRao MD 32
Tuberculin Testing - Limitations
bull False positive reactions are mainly due to
bull - Infection with nontuberculous mycobacteria
bull False negative reactions may be due to
bull - Sever tuberculosis infection (Miliary TB) -Hodgkinrsquos disease
bull - Corticosteroid therapy - Malnutrition -AIDS
bull Children below 5 years of age with no exposure history
bull - Positive test must be regarded suspicious DrTVRao MD 33
Recent Methods for Diagnosis
I ndash BACTEC 460 ( rapid radiometric culture system )
Specimens are cultured in a liquid medium (Middle brook7H9 broth base )containing C14 ndash labeled palmitic acid amp PANTA antibiotic mixture
Growing mycobacteria utilize the acid releasing radioactive CO2 which is measured as growth index (GI) in the BACTEC instrument
The daily increase in GI output is directly proportional to the rate amp amount of growth in the medium
DrTVRao MD 34
TB blood testsbull TB blood tests (also called interferon-gamma
release assays or IGRAs) measure how the immune system reacts to the bacteria that cause TB An IGRA measures how strong a personrsquos immune system reacts to TB bacteria by testing the personrsquos blood in a laboratory
bull Two IGRAs are approved by the US Food and Drug Administration (FDA) and are available in the United States
DrTVRao MD 35
Positive IGRAbull This means that the
person has been infected with TB bacteria Additional tests are needed to determine if the person has latent TB infection or TB disease A health care worker will then provide treatment as needed
DrTVRao MD 36
Negative IGRA
bull This means that the personrsquos blood did not react to the test and that latent TB infection or TB disease is not likely
DrTVRao MD 37
IGRAs are the preferred method of TB infection testing for the following
People who have received bacilli ChalmettendashGueacuterin (BCG) BCG is a vaccine for TB disease People who have a difficult time returning for a second appointment to look for a reaction to the TST
There is no problem with repeated IGRAs
DrTVRao MD 38
III Polymerase Chain Reaction
(PCR) amp Gene probeNucleic acid probes amp nucleic acid amplification
tests in which polymerase enzymes are used to
amplify ( make many copies of specific DNA or
RNA sequences extracted from mycobacterial
cells
Advantages
- Rapid procedure - High sensitivity (1-10
( 3 ndash 4 hours) bacilli ml sputum)
DrTVRao MD 39
Molecular DR testing is particularly useful for
bull Patients suspected or at high risk of having drug-resistant TBvery ill patients for whom drug-susceptibility information might alter case management decisions such as patients who do not get better while taking standard first-line therapy
DrTVRao MD 40
Detection of MDR Tuberculosis
bull Very ill patients for whom drug-susceptibility information might alter case management decisions such as patients who do not get better while taking standard first-line therapy
DrTVRao MD 41
Detection of MDR Tuberculosis
bull outbreak or contact investigations when drug resistance is suspected in the source case or in some severely immunocompromised persons such as HIV-infected persons or those receiving dialysis in which knowledge of drug-susceptibility would be a significant benefit and affect preventive therapy decisions
DrTVRao MD 42
Tuberculosis and HIV infection
bull HIV association has become a threat to the developed countries too
bull HIV association will lead to rapid spread of tuberculosis
DrTVRao MD 43
HIV Considerations
bull HIV is the strongest risk factor for progression to active disease
bull HIV kills CD4+ T Helper cells which normally inhibit M tuberculosis
bull HIV interferes with PPD skin test
bull Protease inhibitors interfere with rifampin
DrTVRao MD 44
Epidemiologybull An ancient disease called as white plague
bull 13 of the world population is infected
bull 2 billion infected
bull Each year 9 lakhs to 1 million are infected
bull Poor nations phase the burnt of the disease
bull In developing world gt 4o of the population is effected
bull 15 million suffer the disease
bull 3 million are highly infective
DrTVRao MD 45
MDR tuberculosis
bull Multidrug resistant tuberculosis has become a global threat
bull In 1993 WHO declared Tuberculosis a Global emergency
bull Animals shed the bacilli in Milk humanrsquos get infected after drinking the unsterilized Milk
bull Pasteurization has reduced the incidence of Bovine tuberculosis
DrTVRao MD 46
Why Tuberculosis continues to be Important
bull Someone in the world is newly infected with TB bacilli every second
bull Overall one-third of the worlds population is currently infected with the TB bacillus
bull 5-10 of people who are infected with TB bacilli (but who are not infected with HIV) become sick or infectious at some time during their life People with HIV and TB infection are much more likely to develop TB
DrTVRao MD 47
bull Programme Created by DrTVRao MD for Medical and Paramedical
Students in Developing world
bull Email
bull doctortvraogmailcom
DrTVRao MD 48
![Page 28: Diagnosis of tuberculosis an Update](https://reader031.fdocuments.in/reader031/viewer/2022032113/55a62b711a28abd5138b48bb/html5/thumbnails/28.jpg)
Tuberculin TestInterpretation A positive test indicates previous exposure and
carriage of TB A negative tuberculin test excludes infection in
suspected persons Tuberculin positive persons may develop
reactivation type of TB Tuberculin negative persons are at risk of gaining
new infection False positive reactions are mainly due to
- Infection with nontuberculous mycobacteria
DrTVRao MD 28
False negative reactions may be due to-
bull False negative reactions may be due to
- Sever tuberculosis infection (Miliary TB) -Hodgkinrsquos disease
bull Corticosteroid therapy - Malnutrition -AIDS
bull Children below 5 years of age with no exposure history
bull Positive test must be regarded suspicious
DrTVRao MD 29
Tuberculin Test( Mantoux Test )
bull Test to be interpreted in relation to clinical evaluation
bull Even the induration of 5 mm to be considered positive when tested on HIV patients
bull Lacks specificity
Positive Test Means
bull This means the personrsquos body was infected with TB bacteria Additional tests are needed to determine if the person has latent TB infection or TB disease A health care worker will then provide treatment as needed
DrTVRao MD 31
Negative Test Means
bull This means the personrsquos body did not react to the test and that latent TB infection or TB disease is not likely
DrTVRao MD 32
Tuberculin Testing - Limitations
bull False positive reactions are mainly due to
bull - Infection with nontuberculous mycobacteria
bull False negative reactions may be due to
bull - Sever tuberculosis infection (Miliary TB) -Hodgkinrsquos disease
bull - Corticosteroid therapy - Malnutrition -AIDS
bull Children below 5 years of age with no exposure history
bull - Positive test must be regarded suspicious DrTVRao MD 33
Recent Methods for Diagnosis
I ndash BACTEC 460 ( rapid radiometric culture system )
Specimens are cultured in a liquid medium (Middle brook7H9 broth base )containing C14 ndash labeled palmitic acid amp PANTA antibiotic mixture
Growing mycobacteria utilize the acid releasing radioactive CO2 which is measured as growth index (GI) in the BACTEC instrument
The daily increase in GI output is directly proportional to the rate amp amount of growth in the medium
DrTVRao MD 34
TB blood testsbull TB blood tests (also called interferon-gamma
release assays or IGRAs) measure how the immune system reacts to the bacteria that cause TB An IGRA measures how strong a personrsquos immune system reacts to TB bacteria by testing the personrsquos blood in a laboratory
bull Two IGRAs are approved by the US Food and Drug Administration (FDA) and are available in the United States
DrTVRao MD 35
Positive IGRAbull This means that the
person has been infected with TB bacteria Additional tests are needed to determine if the person has latent TB infection or TB disease A health care worker will then provide treatment as needed
DrTVRao MD 36
Negative IGRA
bull This means that the personrsquos blood did not react to the test and that latent TB infection or TB disease is not likely
DrTVRao MD 37
IGRAs are the preferred method of TB infection testing for the following
People who have received bacilli ChalmettendashGueacuterin (BCG) BCG is a vaccine for TB disease People who have a difficult time returning for a second appointment to look for a reaction to the TST
There is no problem with repeated IGRAs
DrTVRao MD 38
III Polymerase Chain Reaction
(PCR) amp Gene probeNucleic acid probes amp nucleic acid amplification
tests in which polymerase enzymes are used to
amplify ( make many copies of specific DNA or
RNA sequences extracted from mycobacterial
cells
Advantages
- Rapid procedure - High sensitivity (1-10
( 3 ndash 4 hours) bacilli ml sputum)
DrTVRao MD 39
Molecular DR testing is particularly useful for
bull Patients suspected or at high risk of having drug-resistant TBvery ill patients for whom drug-susceptibility information might alter case management decisions such as patients who do not get better while taking standard first-line therapy
DrTVRao MD 40
Detection of MDR Tuberculosis
bull Very ill patients for whom drug-susceptibility information might alter case management decisions such as patients who do not get better while taking standard first-line therapy
DrTVRao MD 41
Detection of MDR Tuberculosis
bull outbreak or contact investigations when drug resistance is suspected in the source case or in some severely immunocompromised persons such as HIV-infected persons or those receiving dialysis in which knowledge of drug-susceptibility would be a significant benefit and affect preventive therapy decisions
DrTVRao MD 42
Tuberculosis and HIV infection
bull HIV association has become a threat to the developed countries too
bull HIV association will lead to rapid spread of tuberculosis
DrTVRao MD 43
HIV Considerations
bull HIV is the strongest risk factor for progression to active disease
bull HIV kills CD4+ T Helper cells which normally inhibit M tuberculosis
bull HIV interferes with PPD skin test
bull Protease inhibitors interfere with rifampin
DrTVRao MD 44
Epidemiologybull An ancient disease called as white plague
bull 13 of the world population is infected
bull 2 billion infected
bull Each year 9 lakhs to 1 million are infected
bull Poor nations phase the burnt of the disease
bull In developing world gt 4o of the population is effected
bull 15 million suffer the disease
bull 3 million are highly infective
DrTVRao MD 45
MDR tuberculosis
bull Multidrug resistant tuberculosis has become a global threat
bull In 1993 WHO declared Tuberculosis a Global emergency
bull Animals shed the bacilli in Milk humanrsquos get infected after drinking the unsterilized Milk
bull Pasteurization has reduced the incidence of Bovine tuberculosis
DrTVRao MD 46
Why Tuberculosis continues to be Important
bull Someone in the world is newly infected with TB bacilli every second
bull Overall one-third of the worlds population is currently infected with the TB bacillus
bull 5-10 of people who are infected with TB bacilli (but who are not infected with HIV) become sick or infectious at some time during their life People with HIV and TB infection are much more likely to develop TB
DrTVRao MD 47
bull Programme Created by DrTVRao MD for Medical and Paramedical
Students in Developing world
bull Email
bull doctortvraogmailcom
DrTVRao MD 48
![Page 29: Diagnosis of tuberculosis an Update](https://reader031.fdocuments.in/reader031/viewer/2022032113/55a62b711a28abd5138b48bb/html5/thumbnails/29.jpg)
False negative reactions may be due to-
bull False negative reactions may be due to
- Sever tuberculosis infection (Miliary TB) -Hodgkinrsquos disease
bull Corticosteroid therapy - Malnutrition -AIDS
bull Children below 5 years of age with no exposure history
bull Positive test must be regarded suspicious
DrTVRao MD 29
Tuberculin Test( Mantoux Test )
bull Test to be interpreted in relation to clinical evaluation
bull Even the induration of 5 mm to be considered positive when tested on HIV patients
bull Lacks specificity
Positive Test Means
bull This means the personrsquos body was infected with TB bacteria Additional tests are needed to determine if the person has latent TB infection or TB disease A health care worker will then provide treatment as needed
DrTVRao MD 31
Negative Test Means
bull This means the personrsquos body did not react to the test and that latent TB infection or TB disease is not likely
DrTVRao MD 32
Tuberculin Testing - Limitations
bull False positive reactions are mainly due to
bull - Infection with nontuberculous mycobacteria
bull False negative reactions may be due to
bull - Sever tuberculosis infection (Miliary TB) -Hodgkinrsquos disease
bull - Corticosteroid therapy - Malnutrition -AIDS
bull Children below 5 years of age with no exposure history
bull - Positive test must be regarded suspicious DrTVRao MD 33
Recent Methods for Diagnosis
I ndash BACTEC 460 ( rapid radiometric culture system )
Specimens are cultured in a liquid medium (Middle brook7H9 broth base )containing C14 ndash labeled palmitic acid amp PANTA antibiotic mixture
Growing mycobacteria utilize the acid releasing radioactive CO2 which is measured as growth index (GI) in the BACTEC instrument
The daily increase in GI output is directly proportional to the rate amp amount of growth in the medium
DrTVRao MD 34
TB blood testsbull TB blood tests (also called interferon-gamma
release assays or IGRAs) measure how the immune system reacts to the bacteria that cause TB An IGRA measures how strong a personrsquos immune system reacts to TB bacteria by testing the personrsquos blood in a laboratory
bull Two IGRAs are approved by the US Food and Drug Administration (FDA) and are available in the United States
DrTVRao MD 35
Positive IGRAbull This means that the
person has been infected with TB bacteria Additional tests are needed to determine if the person has latent TB infection or TB disease A health care worker will then provide treatment as needed
DrTVRao MD 36
Negative IGRA
bull This means that the personrsquos blood did not react to the test and that latent TB infection or TB disease is not likely
DrTVRao MD 37
IGRAs are the preferred method of TB infection testing for the following
People who have received bacilli ChalmettendashGueacuterin (BCG) BCG is a vaccine for TB disease People who have a difficult time returning for a second appointment to look for a reaction to the TST
There is no problem with repeated IGRAs
DrTVRao MD 38
III Polymerase Chain Reaction
(PCR) amp Gene probeNucleic acid probes amp nucleic acid amplification
tests in which polymerase enzymes are used to
amplify ( make many copies of specific DNA or
RNA sequences extracted from mycobacterial
cells
Advantages
- Rapid procedure - High sensitivity (1-10
( 3 ndash 4 hours) bacilli ml sputum)
DrTVRao MD 39
Molecular DR testing is particularly useful for
bull Patients suspected or at high risk of having drug-resistant TBvery ill patients for whom drug-susceptibility information might alter case management decisions such as patients who do not get better while taking standard first-line therapy
DrTVRao MD 40
Detection of MDR Tuberculosis
bull Very ill patients for whom drug-susceptibility information might alter case management decisions such as patients who do not get better while taking standard first-line therapy
DrTVRao MD 41
Detection of MDR Tuberculosis
bull outbreak or contact investigations when drug resistance is suspected in the source case or in some severely immunocompromised persons such as HIV-infected persons or those receiving dialysis in which knowledge of drug-susceptibility would be a significant benefit and affect preventive therapy decisions
DrTVRao MD 42
Tuberculosis and HIV infection
bull HIV association has become a threat to the developed countries too
bull HIV association will lead to rapid spread of tuberculosis
DrTVRao MD 43
HIV Considerations
bull HIV is the strongest risk factor for progression to active disease
bull HIV kills CD4+ T Helper cells which normally inhibit M tuberculosis
bull HIV interferes with PPD skin test
bull Protease inhibitors interfere with rifampin
DrTVRao MD 44
Epidemiologybull An ancient disease called as white plague
bull 13 of the world population is infected
bull 2 billion infected
bull Each year 9 lakhs to 1 million are infected
bull Poor nations phase the burnt of the disease
bull In developing world gt 4o of the population is effected
bull 15 million suffer the disease
bull 3 million are highly infective
DrTVRao MD 45
MDR tuberculosis
bull Multidrug resistant tuberculosis has become a global threat
bull In 1993 WHO declared Tuberculosis a Global emergency
bull Animals shed the bacilli in Milk humanrsquos get infected after drinking the unsterilized Milk
bull Pasteurization has reduced the incidence of Bovine tuberculosis
DrTVRao MD 46
Why Tuberculosis continues to be Important
bull Someone in the world is newly infected with TB bacilli every second
bull Overall one-third of the worlds population is currently infected with the TB bacillus
bull 5-10 of people who are infected with TB bacilli (but who are not infected with HIV) become sick or infectious at some time during their life People with HIV and TB infection are much more likely to develop TB
DrTVRao MD 47
bull Programme Created by DrTVRao MD for Medical and Paramedical
Students in Developing world
bull Email
bull doctortvraogmailcom
DrTVRao MD 48
![Page 30: Diagnosis of tuberculosis an Update](https://reader031.fdocuments.in/reader031/viewer/2022032113/55a62b711a28abd5138b48bb/html5/thumbnails/30.jpg)
Tuberculin Test( Mantoux Test )
bull Test to be interpreted in relation to clinical evaluation
bull Even the induration of 5 mm to be considered positive when tested on HIV patients
bull Lacks specificity
Positive Test Means
bull This means the personrsquos body was infected with TB bacteria Additional tests are needed to determine if the person has latent TB infection or TB disease A health care worker will then provide treatment as needed
DrTVRao MD 31
Negative Test Means
bull This means the personrsquos body did not react to the test and that latent TB infection or TB disease is not likely
DrTVRao MD 32
Tuberculin Testing - Limitations
bull False positive reactions are mainly due to
bull - Infection with nontuberculous mycobacteria
bull False negative reactions may be due to
bull - Sever tuberculosis infection (Miliary TB) -Hodgkinrsquos disease
bull - Corticosteroid therapy - Malnutrition -AIDS
bull Children below 5 years of age with no exposure history
bull - Positive test must be regarded suspicious DrTVRao MD 33
Recent Methods for Diagnosis
I ndash BACTEC 460 ( rapid radiometric culture system )
Specimens are cultured in a liquid medium (Middle brook7H9 broth base )containing C14 ndash labeled palmitic acid amp PANTA antibiotic mixture
Growing mycobacteria utilize the acid releasing radioactive CO2 which is measured as growth index (GI) in the BACTEC instrument
The daily increase in GI output is directly proportional to the rate amp amount of growth in the medium
DrTVRao MD 34
TB blood testsbull TB blood tests (also called interferon-gamma
release assays or IGRAs) measure how the immune system reacts to the bacteria that cause TB An IGRA measures how strong a personrsquos immune system reacts to TB bacteria by testing the personrsquos blood in a laboratory
bull Two IGRAs are approved by the US Food and Drug Administration (FDA) and are available in the United States
DrTVRao MD 35
Positive IGRAbull This means that the
person has been infected with TB bacteria Additional tests are needed to determine if the person has latent TB infection or TB disease A health care worker will then provide treatment as needed
DrTVRao MD 36
Negative IGRA
bull This means that the personrsquos blood did not react to the test and that latent TB infection or TB disease is not likely
DrTVRao MD 37
IGRAs are the preferred method of TB infection testing for the following
People who have received bacilli ChalmettendashGueacuterin (BCG) BCG is a vaccine for TB disease People who have a difficult time returning for a second appointment to look for a reaction to the TST
There is no problem with repeated IGRAs
DrTVRao MD 38
III Polymerase Chain Reaction
(PCR) amp Gene probeNucleic acid probes amp nucleic acid amplification
tests in which polymerase enzymes are used to
amplify ( make many copies of specific DNA or
RNA sequences extracted from mycobacterial
cells
Advantages
- Rapid procedure - High sensitivity (1-10
( 3 ndash 4 hours) bacilli ml sputum)
DrTVRao MD 39
Molecular DR testing is particularly useful for
bull Patients suspected or at high risk of having drug-resistant TBvery ill patients for whom drug-susceptibility information might alter case management decisions such as patients who do not get better while taking standard first-line therapy
DrTVRao MD 40
Detection of MDR Tuberculosis
bull Very ill patients for whom drug-susceptibility information might alter case management decisions such as patients who do not get better while taking standard first-line therapy
DrTVRao MD 41
Detection of MDR Tuberculosis
bull outbreak or contact investigations when drug resistance is suspected in the source case or in some severely immunocompromised persons such as HIV-infected persons or those receiving dialysis in which knowledge of drug-susceptibility would be a significant benefit and affect preventive therapy decisions
DrTVRao MD 42
Tuberculosis and HIV infection
bull HIV association has become a threat to the developed countries too
bull HIV association will lead to rapid spread of tuberculosis
DrTVRao MD 43
HIV Considerations
bull HIV is the strongest risk factor for progression to active disease
bull HIV kills CD4+ T Helper cells which normally inhibit M tuberculosis
bull HIV interferes with PPD skin test
bull Protease inhibitors interfere with rifampin
DrTVRao MD 44
Epidemiologybull An ancient disease called as white plague
bull 13 of the world population is infected
bull 2 billion infected
bull Each year 9 lakhs to 1 million are infected
bull Poor nations phase the burnt of the disease
bull In developing world gt 4o of the population is effected
bull 15 million suffer the disease
bull 3 million are highly infective
DrTVRao MD 45
MDR tuberculosis
bull Multidrug resistant tuberculosis has become a global threat
bull In 1993 WHO declared Tuberculosis a Global emergency
bull Animals shed the bacilli in Milk humanrsquos get infected after drinking the unsterilized Milk
bull Pasteurization has reduced the incidence of Bovine tuberculosis
DrTVRao MD 46
Why Tuberculosis continues to be Important
bull Someone in the world is newly infected with TB bacilli every second
bull Overall one-third of the worlds population is currently infected with the TB bacillus
bull 5-10 of people who are infected with TB bacilli (but who are not infected with HIV) become sick or infectious at some time during their life People with HIV and TB infection are much more likely to develop TB
DrTVRao MD 47
bull Programme Created by DrTVRao MD for Medical and Paramedical
Students in Developing world
bull Email
bull doctortvraogmailcom
DrTVRao MD 48
![Page 31: Diagnosis of tuberculosis an Update](https://reader031.fdocuments.in/reader031/viewer/2022032113/55a62b711a28abd5138b48bb/html5/thumbnails/31.jpg)
Positive Test Means
bull This means the personrsquos body was infected with TB bacteria Additional tests are needed to determine if the person has latent TB infection or TB disease A health care worker will then provide treatment as needed
DrTVRao MD 31
Negative Test Means
bull This means the personrsquos body did not react to the test and that latent TB infection or TB disease is not likely
DrTVRao MD 32
Tuberculin Testing - Limitations
bull False positive reactions are mainly due to
bull - Infection with nontuberculous mycobacteria
bull False negative reactions may be due to
bull - Sever tuberculosis infection (Miliary TB) -Hodgkinrsquos disease
bull - Corticosteroid therapy - Malnutrition -AIDS
bull Children below 5 years of age with no exposure history
bull - Positive test must be regarded suspicious DrTVRao MD 33
Recent Methods for Diagnosis
I ndash BACTEC 460 ( rapid radiometric culture system )
Specimens are cultured in a liquid medium (Middle brook7H9 broth base )containing C14 ndash labeled palmitic acid amp PANTA antibiotic mixture
Growing mycobacteria utilize the acid releasing radioactive CO2 which is measured as growth index (GI) in the BACTEC instrument
The daily increase in GI output is directly proportional to the rate amp amount of growth in the medium
DrTVRao MD 34
TB blood testsbull TB blood tests (also called interferon-gamma
release assays or IGRAs) measure how the immune system reacts to the bacteria that cause TB An IGRA measures how strong a personrsquos immune system reacts to TB bacteria by testing the personrsquos blood in a laboratory
bull Two IGRAs are approved by the US Food and Drug Administration (FDA) and are available in the United States
DrTVRao MD 35
Positive IGRAbull This means that the
person has been infected with TB bacteria Additional tests are needed to determine if the person has latent TB infection or TB disease A health care worker will then provide treatment as needed
DrTVRao MD 36
Negative IGRA
bull This means that the personrsquos blood did not react to the test and that latent TB infection or TB disease is not likely
DrTVRao MD 37
IGRAs are the preferred method of TB infection testing for the following
People who have received bacilli ChalmettendashGueacuterin (BCG) BCG is a vaccine for TB disease People who have a difficult time returning for a second appointment to look for a reaction to the TST
There is no problem with repeated IGRAs
DrTVRao MD 38
III Polymerase Chain Reaction
(PCR) amp Gene probeNucleic acid probes amp nucleic acid amplification
tests in which polymerase enzymes are used to
amplify ( make many copies of specific DNA or
RNA sequences extracted from mycobacterial
cells
Advantages
- Rapid procedure - High sensitivity (1-10
( 3 ndash 4 hours) bacilli ml sputum)
DrTVRao MD 39
Molecular DR testing is particularly useful for
bull Patients suspected or at high risk of having drug-resistant TBvery ill patients for whom drug-susceptibility information might alter case management decisions such as patients who do not get better while taking standard first-line therapy
DrTVRao MD 40
Detection of MDR Tuberculosis
bull Very ill patients for whom drug-susceptibility information might alter case management decisions such as patients who do not get better while taking standard first-line therapy
DrTVRao MD 41
Detection of MDR Tuberculosis
bull outbreak or contact investigations when drug resistance is suspected in the source case or in some severely immunocompromised persons such as HIV-infected persons or those receiving dialysis in which knowledge of drug-susceptibility would be a significant benefit and affect preventive therapy decisions
DrTVRao MD 42
Tuberculosis and HIV infection
bull HIV association has become a threat to the developed countries too
bull HIV association will lead to rapid spread of tuberculosis
DrTVRao MD 43
HIV Considerations
bull HIV is the strongest risk factor for progression to active disease
bull HIV kills CD4+ T Helper cells which normally inhibit M tuberculosis
bull HIV interferes with PPD skin test
bull Protease inhibitors interfere with rifampin
DrTVRao MD 44
Epidemiologybull An ancient disease called as white plague
bull 13 of the world population is infected
bull 2 billion infected
bull Each year 9 lakhs to 1 million are infected
bull Poor nations phase the burnt of the disease
bull In developing world gt 4o of the population is effected
bull 15 million suffer the disease
bull 3 million are highly infective
DrTVRao MD 45
MDR tuberculosis
bull Multidrug resistant tuberculosis has become a global threat
bull In 1993 WHO declared Tuberculosis a Global emergency
bull Animals shed the bacilli in Milk humanrsquos get infected after drinking the unsterilized Milk
bull Pasteurization has reduced the incidence of Bovine tuberculosis
DrTVRao MD 46
Why Tuberculosis continues to be Important
bull Someone in the world is newly infected with TB bacilli every second
bull Overall one-third of the worlds population is currently infected with the TB bacillus
bull 5-10 of people who are infected with TB bacilli (but who are not infected with HIV) become sick or infectious at some time during their life People with HIV and TB infection are much more likely to develop TB
DrTVRao MD 47
bull Programme Created by DrTVRao MD for Medical and Paramedical
Students in Developing world
bull Email
bull doctortvraogmailcom
DrTVRao MD 48
![Page 32: Diagnosis of tuberculosis an Update](https://reader031.fdocuments.in/reader031/viewer/2022032113/55a62b711a28abd5138b48bb/html5/thumbnails/32.jpg)
Negative Test Means
bull This means the personrsquos body did not react to the test and that latent TB infection or TB disease is not likely
DrTVRao MD 32
Tuberculin Testing - Limitations
bull False positive reactions are mainly due to
bull - Infection with nontuberculous mycobacteria
bull False negative reactions may be due to
bull - Sever tuberculosis infection (Miliary TB) -Hodgkinrsquos disease
bull - Corticosteroid therapy - Malnutrition -AIDS
bull Children below 5 years of age with no exposure history
bull - Positive test must be regarded suspicious DrTVRao MD 33
Recent Methods for Diagnosis
I ndash BACTEC 460 ( rapid radiometric culture system )
Specimens are cultured in a liquid medium (Middle brook7H9 broth base )containing C14 ndash labeled palmitic acid amp PANTA antibiotic mixture
Growing mycobacteria utilize the acid releasing radioactive CO2 which is measured as growth index (GI) in the BACTEC instrument
The daily increase in GI output is directly proportional to the rate amp amount of growth in the medium
DrTVRao MD 34
TB blood testsbull TB blood tests (also called interferon-gamma
release assays or IGRAs) measure how the immune system reacts to the bacteria that cause TB An IGRA measures how strong a personrsquos immune system reacts to TB bacteria by testing the personrsquos blood in a laboratory
bull Two IGRAs are approved by the US Food and Drug Administration (FDA) and are available in the United States
DrTVRao MD 35
Positive IGRAbull This means that the
person has been infected with TB bacteria Additional tests are needed to determine if the person has latent TB infection or TB disease A health care worker will then provide treatment as needed
DrTVRao MD 36
Negative IGRA
bull This means that the personrsquos blood did not react to the test and that latent TB infection or TB disease is not likely
DrTVRao MD 37
IGRAs are the preferred method of TB infection testing for the following
People who have received bacilli ChalmettendashGueacuterin (BCG) BCG is a vaccine for TB disease People who have a difficult time returning for a second appointment to look for a reaction to the TST
There is no problem with repeated IGRAs
DrTVRao MD 38
III Polymerase Chain Reaction
(PCR) amp Gene probeNucleic acid probes amp nucleic acid amplification
tests in which polymerase enzymes are used to
amplify ( make many copies of specific DNA or
RNA sequences extracted from mycobacterial
cells
Advantages
- Rapid procedure - High sensitivity (1-10
( 3 ndash 4 hours) bacilli ml sputum)
DrTVRao MD 39
Molecular DR testing is particularly useful for
bull Patients suspected or at high risk of having drug-resistant TBvery ill patients for whom drug-susceptibility information might alter case management decisions such as patients who do not get better while taking standard first-line therapy
DrTVRao MD 40
Detection of MDR Tuberculosis
bull Very ill patients for whom drug-susceptibility information might alter case management decisions such as patients who do not get better while taking standard first-line therapy
DrTVRao MD 41
Detection of MDR Tuberculosis
bull outbreak or contact investigations when drug resistance is suspected in the source case or in some severely immunocompromised persons such as HIV-infected persons or those receiving dialysis in which knowledge of drug-susceptibility would be a significant benefit and affect preventive therapy decisions
DrTVRao MD 42
Tuberculosis and HIV infection
bull HIV association has become a threat to the developed countries too
bull HIV association will lead to rapid spread of tuberculosis
DrTVRao MD 43
HIV Considerations
bull HIV is the strongest risk factor for progression to active disease
bull HIV kills CD4+ T Helper cells which normally inhibit M tuberculosis
bull HIV interferes with PPD skin test
bull Protease inhibitors interfere with rifampin
DrTVRao MD 44
Epidemiologybull An ancient disease called as white plague
bull 13 of the world population is infected
bull 2 billion infected
bull Each year 9 lakhs to 1 million are infected
bull Poor nations phase the burnt of the disease
bull In developing world gt 4o of the population is effected
bull 15 million suffer the disease
bull 3 million are highly infective
DrTVRao MD 45
MDR tuberculosis
bull Multidrug resistant tuberculosis has become a global threat
bull In 1993 WHO declared Tuberculosis a Global emergency
bull Animals shed the bacilli in Milk humanrsquos get infected after drinking the unsterilized Milk
bull Pasteurization has reduced the incidence of Bovine tuberculosis
DrTVRao MD 46
Why Tuberculosis continues to be Important
bull Someone in the world is newly infected with TB bacilli every second
bull Overall one-third of the worlds population is currently infected with the TB bacillus
bull 5-10 of people who are infected with TB bacilli (but who are not infected with HIV) become sick or infectious at some time during their life People with HIV and TB infection are much more likely to develop TB
DrTVRao MD 47
bull Programme Created by DrTVRao MD for Medical and Paramedical
Students in Developing world
bull Email
bull doctortvraogmailcom
DrTVRao MD 48
![Page 33: Diagnosis of tuberculosis an Update](https://reader031.fdocuments.in/reader031/viewer/2022032113/55a62b711a28abd5138b48bb/html5/thumbnails/33.jpg)
Tuberculin Testing - Limitations
bull False positive reactions are mainly due to
bull - Infection with nontuberculous mycobacteria
bull False negative reactions may be due to
bull - Sever tuberculosis infection (Miliary TB) -Hodgkinrsquos disease
bull - Corticosteroid therapy - Malnutrition -AIDS
bull Children below 5 years of age with no exposure history
bull - Positive test must be regarded suspicious DrTVRao MD 33
Recent Methods for Diagnosis
I ndash BACTEC 460 ( rapid radiometric culture system )
Specimens are cultured in a liquid medium (Middle brook7H9 broth base )containing C14 ndash labeled palmitic acid amp PANTA antibiotic mixture
Growing mycobacteria utilize the acid releasing radioactive CO2 which is measured as growth index (GI) in the BACTEC instrument
The daily increase in GI output is directly proportional to the rate amp amount of growth in the medium
DrTVRao MD 34
TB blood testsbull TB blood tests (also called interferon-gamma
release assays or IGRAs) measure how the immune system reacts to the bacteria that cause TB An IGRA measures how strong a personrsquos immune system reacts to TB bacteria by testing the personrsquos blood in a laboratory
bull Two IGRAs are approved by the US Food and Drug Administration (FDA) and are available in the United States
DrTVRao MD 35
Positive IGRAbull This means that the
person has been infected with TB bacteria Additional tests are needed to determine if the person has latent TB infection or TB disease A health care worker will then provide treatment as needed
DrTVRao MD 36
Negative IGRA
bull This means that the personrsquos blood did not react to the test and that latent TB infection or TB disease is not likely
DrTVRao MD 37
IGRAs are the preferred method of TB infection testing for the following
People who have received bacilli ChalmettendashGueacuterin (BCG) BCG is a vaccine for TB disease People who have a difficult time returning for a second appointment to look for a reaction to the TST
There is no problem with repeated IGRAs
DrTVRao MD 38
III Polymerase Chain Reaction
(PCR) amp Gene probeNucleic acid probes amp nucleic acid amplification
tests in which polymerase enzymes are used to
amplify ( make many copies of specific DNA or
RNA sequences extracted from mycobacterial
cells
Advantages
- Rapid procedure - High sensitivity (1-10
( 3 ndash 4 hours) bacilli ml sputum)
DrTVRao MD 39
Molecular DR testing is particularly useful for
bull Patients suspected or at high risk of having drug-resistant TBvery ill patients for whom drug-susceptibility information might alter case management decisions such as patients who do not get better while taking standard first-line therapy
DrTVRao MD 40
Detection of MDR Tuberculosis
bull Very ill patients for whom drug-susceptibility information might alter case management decisions such as patients who do not get better while taking standard first-line therapy
DrTVRao MD 41
Detection of MDR Tuberculosis
bull outbreak or contact investigations when drug resistance is suspected in the source case or in some severely immunocompromised persons such as HIV-infected persons or those receiving dialysis in which knowledge of drug-susceptibility would be a significant benefit and affect preventive therapy decisions
DrTVRao MD 42
Tuberculosis and HIV infection
bull HIV association has become a threat to the developed countries too
bull HIV association will lead to rapid spread of tuberculosis
DrTVRao MD 43
HIV Considerations
bull HIV is the strongest risk factor for progression to active disease
bull HIV kills CD4+ T Helper cells which normally inhibit M tuberculosis
bull HIV interferes with PPD skin test
bull Protease inhibitors interfere with rifampin
DrTVRao MD 44
Epidemiologybull An ancient disease called as white plague
bull 13 of the world population is infected
bull 2 billion infected
bull Each year 9 lakhs to 1 million are infected
bull Poor nations phase the burnt of the disease
bull In developing world gt 4o of the population is effected
bull 15 million suffer the disease
bull 3 million are highly infective
DrTVRao MD 45
MDR tuberculosis
bull Multidrug resistant tuberculosis has become a global threat
bull In 1993 WHO declared Tuberculosis a Global emergency
bull Animals shed the bacilli in Milk humanrsquos get infected after drinking the unsterilized Milk
bull Pasteurization has reduced the incidence of Bovine tuberculosis
DrTVRao MD 46
Why Tuberculosis continues to be Important
bull Someone in the world is newly infected with TB bacilli every second
bull Overall one-third of the worlds population is currently infected with the TB bacillus
bull 5-10 of people who are infected with TB bacilli (but who are not infected with HIV) become sick or infectious at some time during their life People with HIV and TB infection are much more likely to develop TB
DrTVRao MD 47
bull Programme Created by DrTVRao MD for Medical and Paramedical
Students in Developing world
bull Email
bull doctortvraogmailcom
DrTVRao MD 48
![Page 34: Diagnosis of tuberculosis an Update](https://reader031.fdocuments.in/reader031/viewer/2022032113/55a62b711a28abd5138b48bb/html5/thumbnails/34.jpg)
Recent Methods for Diagnosis
I ndash BACTEC 460 ( rapid radiometric culture system )
Specimens are cultured in a liquid medium (Middle brook7H9 broth base )containing C14 ndash labeled palmitic acid amp PANTA antibiotic mixture
Growing mycobacteria utilize the acid releasing radioactive CO2 which is measured as growth index (GI) in the BACTEC instrument
The daily increase in GI output is directly proportional to the rate amp amount of growth in the medium
DrTVRao MD 34
TB blood testsbull TB blood tests (also called interferon-gamma
release assays or IGRAs) measure how the immune system reacts to the bacteria that cause TB An IGRA measures how strong a personrsquos immune system reacts to TB bacteria by testing the personrsquos blood in a laboratory
bull Two IGRAs are approved by the US Food and Drug Administration (FDA) and are available in the United States
DrTVRao MD 35
Positive IGRAbull This means that the
person has been infected with TB bacteria Additional tests are needed to determine if the person has latent TB infection or TB disease A health care worker will then provide treatment as needed
DrTVRao MD 36
Negative IGRA
bull This means that the personrsquos blood did not react to the test and that latent TB infection or TB disease is not likely
DrTVRao MD 37
IGRAs are the preferred method of TB infection testing for the following
People who have received bacilli ChalmettendashGueacuterin (BCG) BCG is a vaccine for TB disease People who have a difficult time returning for a second appointment to look for a reaction to the TST
There is no problem with repeated IGRAs
DrTVRao MD 38
III Polymerase Chain Reaction
(PCR) amp Gene probeNucleic acid probes amp nucleic acid amplification
tests in which polymerase enzymes are used to
amplify ( make many copies of specific DNA or
RNA sequences extracted from mycobacterial
cells
Advantages
- Rapid procedure - High sensitivity (1-10
( 3 ndash 4 hours) bacilli ml sputum)
DrTVRao MD 39
Molecular DR testing is particularly useful for
bull Patients suspected or at high risk of having drug-resistant TBvery ill patients for whom drug-susceptibility information might alter case management decisions such as patients who do not get better while taking standard first-line therapy
DrTVRao MD 40
Detection of MDR Tuberculosis
bull Very ill patients for whom drug-susceptibility information might alter case management decisions such as patients who do not get better while taking standard first-line therapy
DrTVRao MD 41
Detection of MDR Tuberculosis
bull outbreak or contact investigations when drug resistance is suspected in the source case or in some severely immunocompromised persons such as HIV-infected persons or those receiving dialysis in which knowledge of drug-susceptibility would be a significant benefit and affect preventive therapy decisions
DrTVRao MD 42
Tuberculosis and HIV infection
bull HIV association has become a threat to the developed countries too
bull HIV association will lead to rapid spread of tuberculosis
DrTVRao MD 43
HIV Considerations
bull HIV is the strongest risk factor for progression to active disease
bull HIV kills CD4+ T Helper cells which normally inhibit M tuberculosis
bull HIV interferes with PPD skin test
bull Protease inhibitors interfere with rifampin
DrTVRao MD 44
Epidemiologybull An ancient disease called as white plague
bull 13 of the world population is infected
bull 2 billion infected
bull Each year 9 lakhs to 1 million are infected
bull Poor nations phase the burnt of the disease
bull In developing world gt 4o of the population is effected
bull 15 million suffer the disease
bull 3 million are highly infective
DrTVRao MD 45
MDR tuberculosis
bull Multidrug resistant tuberculosis has become a global threat
bull In 1993 WHO declared Tuberculosis a Global emergency
bull Animals shed the bacilli in Milk humanrsquos get infected after drinking the unsterilized Milk
bull Pasteurization has reduced the incidence of Bovine tuberculosis
DrTVRao MD 46
Why Tuberculosis continues to be Important
bull Someone in the world is newly infected with TB bacilli every second
bull Overall one-third of the worlds population is currently infected with the TB bacillus
bull 5-10 of people who are infected with TB bacilli (but who are not infected with HIV) become sick or infectious at some time during their life People with HIV and TB infection are much more likely to develop TB
DrTVRao MD 47
bull Programme Created by DrTVRao MD for Medical and Paramedical
Students in Developing world
bull Email
bull doctortvraogmailcom
DrTVRao MD 48
![Page 35: Diagnosis of tuberculosis an Update](https://reader031.fdocuments.in/reader031/viewer/2022032113/55a62b711a28abd5138b48bb/html5/thumbnails/35.jpg)
TB blood testsbull TB blood tests (also called interferon-gamma
release assays or IGRAs) measure how the immune system reacts to the bacteria that cause TB An IGRA measures how strong a personrsquos immune system reacts to TB bacteria by testing the personrsquos blood in a laboratory
bull Two IGRAs are approved by the US Food and Drug Administration (FDA) and are available in the United States
DrTVRao MD 35
Positive IGRAbull This means that the
person has been infected with TB bacteria Additional tests are needed to determine if the person has latent TB infection or TB disease A health care worker will then provide treatment as needed
DrTVRao MD 36
Negative IGRA
bull This means that the personrsquos blood did not react to the test and that latent TB infection or TB disease is not likely
DrTVRao MD 37
IGRAs are the preferred method of TB infection testing for the following
People who have received bacilli ChalmettendashGueacuterin (BCG) BCG is a vaccine for TB disease People who have a difficult time returning for a second appointment to look for a reaction to the TST
There is no problem with repeated IGRAs
DrTVRao MD 38
III Polymerase Chain Reaction
(PCR) amp Gene probeNucleic acid probes amp nucleic acid amplification
tests in which polymerase enzymes are used to
amplify ( make many copies of specific DNA or
RNA sequences extracted from mycobacterial
cells
Advantages
- Rapid procedure - High sensitivity (1-10
( 3 ndash 4 hours) bacilli ml sputum)
DrTVRao MD 39
Molecular DR testing is particularly useful for
bull Patients suspected or at high risk of having drug-resistant TBvery ill patients for whom drug-susceptibility information might alter case management decisions such as patients who do not get better while taking standard first-line therapy
DrTVRao MD 40
Detection of MDR Tuberculosis
bull Very ill patients for whom drug-susceptibility information might alter case management decisions such as patients who do not get better while taking standard first-line therapy
DrTVRao MD 41
Detection of MDR Tuberculosis
bull outbreak or contact investigations when drug resistance is suspected in the source case or in some severely immunocompromised persons such as HIV-infected persons or those receiving dialysis in which knowledge of drug-susceptibility would be a significant benefit and affect preventive therapy decisions
DrTVRao MD 42
Tuberculosis and HIV infection
bull HIV association has become a threat to the developed countries too
bull HIV association will lead to rapid spread of tuberculosis
DrTVRao MD 43
HIV Considerations
bull HIV is the strongest risk factor for progression to active disease
bull HIV kills CD4+ T Helper cells which normally inhibit M tuberculosis
bull HIV interferes with PPD skin test
bull Protease inhibitors interfere with rifampin
DrTVRao MD 44
Epidemiologybull An ancient disease called as white plague
bull 13 of the world population is infected
bull 2 billion infected
bull Each year 9 lakhs to 1 million are infected
bull Poor nations phase the burnt of the disease
bull In developing world gt 4o of the population is effected
bull 15 million suffer the disease
bull 3 million are highly infective
DrTVRao MD 45
MDR tuberculosis
bull Multidrug resistant tuberculosis has become a global threat
bull In 1993 WHO declared Tuberculosis a Global emergency
bull Animals shed the bacilli in Milk humanrsquos get infected after drinking the unsterilized Milk
bull Pasteurization has reduced the incidence of Bovine tuberculosis
DrTVRao MD 46
Why Tuberculosis continues to be Important
bull Someone in the world is newly infected with TB bacilli every second
bull Overall one-third of the worlds population is currently infected with the TB bacillus
bull 5-10 of people who are infected with TB bacilli (but who are not infected with HIV) become sick or infectious at some time during their life People with HIV and TB infection are much more likely to develop TB
DrTVRao MD 47
bull Programme Created by DrTVRao MD for Medical and Paramedical
Students in Developing world
bull Email
bull doctortvraogmailcom
DrTVRao MD 48
![Page 36: Diagnosis of tuberculosis an Update](https://reader031.fdocuments.in/reader031/viewer/2022032113/55a62b711a28abd5138b48bb/html5/thumbnails/36.jpg)
Positive IGRAbull This means that the
person has been infected with TB bacteria Additional tests are needed to determine if the person has latent TB infection or TB disease A health care worker will then provide treatment as needed
DrTVRao MD 36
Negative IGRA
bull This means that the personrsquos blood did not react to the test and that latent TB infection or TB disease is not likely
DrTVRao MD 37
IGRAs are the preferred method of TB infection testing for the following
People who have received bacilli ChalmettendashGueacuterin (BCG) BCG is a vaccine for TB disease People who have a difficult time returning for a second appointment to look for a reaction to the TST
There is no problem with repeated IGRAs
DrTVRao MD 38
III Polymerase Chain Reaction
(PCR) amp Gene probeNucleic acid probes amp nucleic acid amplification
tests in which polymerase enzymes are used to
amplify ( make many copies of specific DNA or
RNA sequences extracted from mycobacterial
cells
Advantages
- Rapid procedure - High sensitivity (1-10
( 3 ndash 4 hours) bacilli ml sputum)
DrTVRao MD 39
Molecular DR testing is particularly useful for
bull Patients suspected or at high risk of having drug-resistant TBvery ill patients for whom drug-susceptibility information might alter case management decisions such as patients who do not get better while taking standard first-line therapy
DrTVRao MD 40
Detection of MDR Tuberculosis
bull Very ill patients for whom drug-susceptibility information might alter case management decisions such as patients who do not get better while taking standard first-line therapy
DrTVRao MD 41
Detection of MDR Tuberculosis
bull outbreak or contact investigations when drug resistance is suspected in the source case or in some severely immunocompromised persons such as HIV-infected persons or those receiving dialysis in which knowledge of drug-susceptibility would be a significant benefit and affect preventive therapy decisions
DrTVRao MD 42
Tuberculosis and HIV infection
bull HIV association has become a threat to the developed countries too
bull HIV association will lead to rapid spread of tuberculosis
DrTVRao MD 43
HIV Considerations
bull HIV is the strongest risk factor for progression to active disease
bull HIV kills CD4+ T Helper cells which normally inhibit M tuberculosis
bull HIV interferes with PPD skin test
bull Protease inhibitors interfere with rifampin
DrTVRao MD 44
Epidemiologybull An ancient disease called as white plague
bull 13 of the world population is infected
bull 2 billion infected
bull Each year 9 lakhs to 1 million are infected
bull Poor nations phase the burnt of the disease
bull In developing world gt 4o of the population is effected
bull 15 million suffer the disease
bull 3 million are highly infective
DrTVRao MD 45
MDR tuberculosis
bull Multidrug resistant tuberculosis has become a global threat
bull In 1993 WHO declared Tuberculosis a Global emergency
bull Animals shed the bacilli in Milk humanrsquos get infected after drinking the unsterilized Milk
bull Pasteurization has reduced the incidence of Bovine tuberculosis
DrTVRao MD 46
Why Tuberculosis continues to be Important
bull Someone in the world is newly infected with TB bacilli every second
bull Overall one-third of the worlds population is currently infected with the TB bacillus
bull 5-10 of people who are infected with TB bacilli (but who are not infected with HIV) become sick or infectious at some time during their life People with HIV and TB infection are much more likely to develop TB
DrTVRao MD 47
bull Programme Created by DrTVRao MD for Medical and Paramedical
Students in Developing world
bull Email
bull doctortvraogmailcom
DrTVRao MD 48
![Page 37: Diagnosis of tuberculosis an Update](https://reader031.fdocuments.in/reader031/viewer/2022032113/55a62b711a28abd5138b48bb/html5/thumbnails/37.jpg)
Negative IGRA
bull This means that the personrsquos blood did not react to the test and that latent TB infection or TB disease is not likely
DrTVRao MD 37
IGRAs are the preferred method of TB infection testing for the following
People who have received bacilli ChalmettendashGueacuterin (BCG) BCG is a vaccine for TB disease People who have a difficult time returning for a second appointment to look for a reaction to the TST
There is no problem with repeated IGRAs
DrTVRao MD 38
III Polymerase Chain Reaction
(PCR) amp Gene probeNucleic acid probes amp nucleic acid amplification
tests in which polymerase enzymes are used to
amplify ( make many copies of specific DNA or
RNA sequences extracted from mycobacterial
cells
Advantages
- Rapid procedure - High sensitivity (1-10
( 3 ndash 4 hours) bacilli ml sputum)
DrTVRao MD 39
Molecular DR testing is particularly useful for
bull Patients suspected or at high risk of having drug-resistant TBvery ill patients for whom drug-susceptibility information might alter case management decisions such as patients who do not get better while taking standard first-line therapy
DrTVRao MD 40
Detection of MDR Tuberculosis
bull Very ill patients for whom drug-susceptibility information might alter case management decisions such as patients who do not get better while taking standard first-line therapy
DrTVRao MD 41
Detection of MDR Tuberculosis
bull outbreak or contact investigations when drug resistance is suspected in the source case or in some severely immunocompromised persons such as HIV-infected persons or those receiving dialysis in which knowledge of drug-susceptibility would be a significant benefit and affect preventive therapy decisions
DrTVRao MD 42
Tuberculosis and HIV infection
bull HIV association has become a threat to the developed countries too
bull HIV association will lead to rapid spread of tuberculosis
DrTVRao MD 43
HIV Considerations
bull HIV is the strongest risk factor for progression to active disease
bull HIV kills CD4+ T Helper cells which normally inhibit M tuberculosis
bull HIV interferes with PPD skin test
bull Protease inhibitors interfere with rifampin
DrTVRao MD 44
Epidemiologybull An ancient disease called as white plague
bull 13 of the world population is infected
bull 2 billion infected
bull Each year 9 lakhs to 1 million are infected
bull Poor nations phase the burnt of the disease
bull In developing world gt 4o of the population is effected
bull 15 million suffer the disease
bull 3 million are highly infective
DrTVRao MD 45
MDR tuberculosis
bull Multidrug resistant tuberculosis has become a global threat
bull In 1993 WHO declared Tuberculosis a Global emergency
bull Animals shed the bacilli in Milk humanrsquos get infected after drinking the unsterilized Milk
bull Pasteurization has reduced the incidence of Bovine tuberculosis
DrTVRao MD 46
Why Tuberculosis continues to be Important
bull Someone in the world is newly infected with TB bacilli every second
bull Overall one-third of the worlds population is currently infected with the TB bacillus
bull 5-10 of people who are infected with TB bacilli (but who are not infected with HIV) become sick or infectious at some time during their life People with HIV and TB infection are much more likely to develop TB
DrTVRao MD 47
bull Programme Created by DrTVRao MD for Medical and Paramedical
Students in Developing world
bull Email
bull doctortvraogmailcom
DrTVRao MD 48
![Page 38: Diagnosis of tuberculosis an Update](https://reader031.fdocuments.in/reader031/viewer/2022032113/55a62b711a28abd5138b48bb/html5/thumbnails/38.jpg)
IGRAs are the preferred method of TB infection testing for the following
People who have received bacilli ChalmettendashGueacuterin (BCG) BCG is a vaccine for TB disease People who have a difficult time returning for a second appointment to look for a reaction to the TST
There is no problem with repeated IGRAs
DrTVRao MD 38
III Polymerase Chain Reaction
(PCR) amp Gene probeNucleic acid probes amp nucleic acid amplification
tests in which polymerase enzymes are used to
amplify ( make many copies of specific DNA or
RNA sequences extracted from mycobacterial
cells
Advantages
- Rapid procedure - High sensitivity (1-10
( 3 ndash 4 hours) bacilli ml sputum)
DrTVRao MD 39
Molecular DR testing is particularly useful for
bull Patients suspected or at high risk of having drug-resistant TBvery ill patients for whom drug-susceptibility information might alter case management decisions such as patients who do not get better while taking standard first-line therapy
DrTVRao MD 40
Detection of MDR Tuberculosis
bull Very ill patients for whom drug-susceptibility information might alter case management decisions such as patients who do not get better while taking standard first-line therapy
DrTVRao MD 41
Detection of MDR Tuberculosis
bull outbreak or contact investigations when drug resistance is suspected in the source case or in some severely immunocompromised persons such as HIV-infected persons or those receiving dialysis in which knowledge of drug-susceptibility would be a significant benefit and affect preventive therapy decisions
DrTVRao MD 42
Tuberculosis and HIV infection
bull HIV association has become a threat to the developed countries too
bull HIV association will lead to rapid spread of tuberculosis
DrTVRao MD 43
HIV Considerations
bull HIV is the strongest risk factor for progression to active disease
bull HIV kills CD4+ T Helper cells which normally inhibit M tuberculosis
bull HIV interferes with PPD skin test
bull Protease inhibitors interfere with rifampin
DrTVRao MD 44
Epidemiologybull An ancient disease called as white plague
bull 13 of the world population is infected
bull 2 billion infected
bull Each year 9 lakhs to 1 million are infected
bull Poor nations phase the burnt of the disease
bull In developing world gt 4o of the population is effected
bull 15 million suffer the disease
bull 3 million are highly infective
DrTVRao MD 45
MDR tuberculosis
bull Multidrug resistant tuberculosis has become a global threat
bull In 1993 WHO declared Tuberculosis a Global emergency
bull Animals shed the bacilli in Milk humanrsquos get infected after drinking the unsterilized Milk
bull Pasteurization has reduced the incidence of Bovine tuberculosis
DrTVRao MD 46
Why Tuberculosis continues to be Important
bull Someone in the world is newly infected with TB bacilli every second
bull Overall one-third of the worlds population is currently infected with the TB bacillus
bull 5-10 of people who are infected with TB bacilli (but who are not infected with HIV) become sick or infectious at some time during their life People with HIV and TB infection are much more likely to develop TB
DrTVRao MD 47
bull Programme Created by DrTVRao MD for Medical and Paramedical
Students in Developing world
bull Email
bull doctortvraogmailcom
DrTVRao MD 48
![Page 39: Diagnosis of tuberculosis an Update](https://reader031.fdocuments.in/reader031/viewer/2022032113/55a62b711a28abd5138b48bb/html5/thumbnails/39.jpg)
III Polymerase Chain Reaction
(PCR) amp Gene probeNucleic acid probes amp nucleic acid amplification
tests in which polymerase enzymes are used to
amplify ( make many copies of specific DNA or
RNA sequences extracted from mycobacterial
cells
Advantages
- Rapid procedure - High sensitivity (1-10
( 3 ndash 4 hours) bacilli ml sputum)
DrTVRao MD 39
Molecular DR testing is particularly useful for
bull Patients suspected or at high risk of having drug-resistant TBvery ill patients for whom drug-susceptibility information might alter case management decisions such as patients who do not get better while taking standard first-line therapy
DrTVRao MD 40
Detection of MDR Tuberculosis
bull Very ill patients for whom drug-susceptibility information might alter case management decisions such as patients who do not get better while taking standard first-line therapy
DrTVRao MD 41
Detection of MDR Tuberculosis
bull outbreak or contact investigations when drug resistance is suspected in the source case or in some severely immunocompromised persons such as HIV-infected persons or those receiving dialysis in which knowledge of drug-susceptibility would be a significant benefit and affect preventive therapy decisions
DrTVRao MD 42
Tuberculosis and HIV infection
bull HIV association has become a threat to the developed countries too
bull HIV association will lead to rapid spread of tuberculosis
DrTVRao MD 43
HIV Considerations
bull HIV is the strongest risk factor for progression to active disease
bull HIV kills CD4+ T Helper cells which normally inhibit M tuberculosis
bull HIV interferes with PPD skin test
bull Protease inhibitors interfere with rifampin
DrTVRao MD 44
Epidemiologybull An ancient disease called as white plague
bull 13 of the world population is infected
bull 2 billion infected
bull Each year 9 lakhs to 1 million are infected
bull Poor nations phase the burnt of the disease
bull In developing world gt 4o of the population is effected
bull 15 million suffer the disease
bull 3 million are highly infective
DrTVRao MD 45
MDR tuberculosis
bull Multidrug resistant tuberculosis has become a global threat
bull In 1993 WHO declared Tuberculosis a Global emergency
bull Animals shed the bacilli in Milk humanrsquos get infected after drinking the unsterilized Milk
bull Pasteurization has reduced the incidence of Bovine tuberculosis
DrTVRao MD 46
Why Tuberculosis continues to be Important
bull Someone in the world is newly infected with TB bacilli every second
bull Overall one-third of the worlds population is currently infected with the TB bacillus
bull 5-10 of people who are infected with TB bacilli (but who are not infected with HIV) become sick or infectious at some time during their life People with HIV and TB infection are much more likely to develop TB
DrTVRao MD 47
bull Programme Created by DrTVRao MD for Medical and Paramedical
Students in Developing world
bull Email
bull doctortvraogmailcom
DrTVRao MD 48
![Page 40: Diagnosis of tuberculosis an Update](https://reader031.fdocuments.in/reader031/viewer/2022032113/55a62b711a28abd5138b48bb/html5/thumbnails/40.jpg)
Molecular DR testing is particularly useful for
bull Patients suspected or at high risk of having drug-resistant TBvery ill patients for whom drug-susceptibility information might alter case management decisions such as patients who do not get better while taking standard first-line therapy
DrTVRao MD 40
Detection of MDR Tuberculosis
bull Very ill patients for whom drug-susceptibility information might alter case management decisions such as patients who do not get better while taking standard first-line therapy
DrTVRao MD 41
Detection of MDR Tuberculosis
bull outbreak or contact investigations when drug resistance is suspected in the source case or in some severely immunocompromised persons such as HIV-infected persons or those receiving dialysis in which knowledge of drug-susceptibility would be a significant benefit and affect preventive therapy decisions
DrTVRao MD 42
Tuberculosis and HIV infection
bull HIV association has become a threat to the developed countries too
bull HIV association will lead to rapid spread of tuberculosis
DrTVRao MD 43
HIV Considerations
bull HIV is the strongest risk factor for progression to active disease
bull HIV kills CD4+ T Helper cells which normally inhibit M tuberculosis
bull HIV interferes with PPD skin test
bull Protease inhibitors interfere with rifampin
DrTVRao MD 44
Epidemiologybull An ancient disease called as white plague
bull 13 of the world population is infected
bull 2 billion infected
bull Each year 9 lakhs to 1 million are infected
bull Poor nations phase the burnt of the disease
bull In developing world gt 4o of the population is effected
bull 15 million suffer the disease
bull 3 million are highly infective
DrTVRao MD 45
MDR tuberculosis
bull Multidrug resistant tuberculosis has become a global threat
bull In 1993 WHO declared Tuberculosis a Global emergency
bull Animals shed the bacilli in Milk humanrsquos get infected after drinking the unsterilized Milk
bull Pasteurization has reduced the incidence of Bovine tuberculosis
DrTVRao MD 46
Why Tuberculosis continues to be Important
bull Someone in the world is newly infected with TB bacilli every second
bull Overall one-third of the worlds population is currently infected with the TB bacillus
bull 5-10 of people who are infected with TB bacilli (but who are not infected with HIV) become sick or infectious at some time during their life People with HIV and TB infection are much more likely to develop TB
DrTVRao MD 47
bull Programme Created by DrTVRao MD for Medical and Paramedical
Students in Developing world
bull Email
bull doctortvraogmailcom
DrTVRao MD 48
![Page 41: Diagnosis of tuberculosis an Update](https://reader031.fdocuments.in/reader031/viewer/2022032113/55a62b711a28abd5138b48bb/html5/thumbnails/41.jpg)
Detection of MDR Tuberculosis
bull Very ill patients for whom drug-susceptibility information might alter case management decisions such as patients who do not get better while taking standard first-line therapy
DrTVRao MD 41
Detection of MDR Tuberculosis
bull outbreak or contact investigations when drug resistance is suspected in the source case or in some severely immunocompromised persons such as HIV-infected persons or those receiving dialysis in which knowledge of drug-susceptibility would be a significant benefit and affect preventive therapy decisions
DrTVRao MD 42
Tuberculosis and HIV infection
bull HIV association has become a threat to the developed countries too
bull HIV association will lead to rapid spread of tuberculosis
DrTVRao MD 43
HIV Considerations
bull HIV is the strongest risk factor for progression to active disease
bull HIV kills CD4+ T Helper cells which normally inhibit M tuberculosis
bull HIV interferes with PPD skin test
bull Protease inhibitors interfere with rifampin
DrTVRao MD 44
Epidemiologybull An ancient disease called as white plague
bull 13 of the world population is infected
bull 2 billion infected
bull Each year 9 lakhs to 1 million are infected
bull Poor nations phase the burnt of the disease
bull In developing world gt 4o of the population is effected
bull 15 million suffer the disease
bull 3 million are highly infective
DrTVRao MD 45
MDR tuberculosis
bull Multidrug resistant tuberculosis has become a global threat
bull In 1993 WHO declared Tuberculosis a Global emergency
bull Animals shed the bacilli in Milk humanrsquos get infected after drinking the unsterilized Milk
bull Pasteurization has reduced the incidence of Bovine tuberculosis
DrTVRao MD 46
Why Tuberculosis continues to be Important
bull Someone in the world is newly infected with TB bacilli every second
bull Overall one-third of the worlds population is currently infected with the TB bacillus
bull 5-10 of people who are infected with TB bacilli (but who are not infected with HIV) become sick or infectious at some time during their life People with HIV and TB infection are much more likely to develop TB
DrTVRao MD 47
bull Programme Created by DrTVRao MD for Medical and Paramedical
Students in Developing world
bull Email
bull doctortvraogmailcom
DrTVRao MD 48
![Page 42: Diagnosis of tuberculosis an Update](https://reader031.fdocuments.in/reader031/viewer/2022032113/55a62b711a28abd5138b48bb/html5/thumbnails/42.jpg)
Detection of MDR Tuberculosis
bull outbreak or contact investigations when drug resistance is suspected in the source case or in some severely immunocompromised persons such as HIV-infected persons or those receiving dialysis in which knowledge of drug-susceptibility would be a significant benefit and affect preventive therapy decisions
DrTVRao MD 42
Tuberculosis and HIV infection
bull HIV association has become a threat to the developed countries too
bull HIV association will lead to rapid spread of tuberculosis
DrTVRao MD 43
HIV Considerations
bull HIV is the strongest risk factor for progression to active disease
bull HIV kills CD4+ T Helper cells which normally inhibit M tuberculosis
bull HIV interferes with PPD skin test
bull Protease inhibitors interfere with rifampin
DrTVRao MD 44
Epidemiologybull An ancient disease called as white plague
bull 13 of the world population is infected
bull 2 billion infected
bull Each year 9 lakhs to 1 million are infected
bull Poor nations phase the burnt of the disease
bull In developing world gt 4o of the population is effected
bull 15 million suffer the disease
bull 3 million are highly infective
DrTVRao MD 45
MDR tuberculosis
bull Multidrug resistant tuberculosis has become a global threat
bull In 1993 WHO declared Tuberculosis a Global emergency
bull Animals shed the bacilli in Milk humanrsquos get infected after drinking the unsterilized Milk
bull Pasteurization has reduced the incidence of Bovine tuberculosis
DrTVRao MD 46
Why Tuberculosis continues to be Important
bull Someone in the world is newly infected with TB bacilli every second
bull Overall one-third of the worlds population is currently infected with the TB bacillus
bull 5-10 of people who are infected with TB bacilli (but who are not infected with HIV) become sick or infectious at some time during their life People with HIV and TB infection are much more likely to develop TB
DrTVRao MD 47
bull Programme Created by DrTVRao MD for Medical and Paramedical
Students in Developing world
bull Email
bull doctortvraogmailcom
DrTVRao MD 48
![Page 43: Diagnosis of tuberculosis an Update](https://reader031.fdocuments.in/reader031/viewer/2022032113/55a62b711a28abd5138b48bb/html5/thumbnails/43.jpg)
Tuberculosis and HIV infection
bull HIV association has become a threat to the developed countries too
bull HIV association will lead to rapid spread of tuberculosis
DrTVRao MD 43
HIV Considerations
bull HIV is the strongest risk factor for progression to active disease
bull HIV kills CD4+ T Helper cells which normally inhibit M tuberculosis
bull HIV interferes with PPD skin test
bull Protease inhibitors interfere with rifampin
DrTVRao MD 44
Epidemiologybull An ancient disease called as white plague
bull 13 of the world population is infected
bull 2 billion infected
bull Each year 9 lakhs to 1 million are infected
bull Poor nations phase the burnt of the disease
bull In developing world gt 4o of the population is effected
bull 15 million suffer the disease
bull 3 million are highly infective
DrTVRao MD 45
MDR tuberculosis
bull Multidrug resistant tuberculosis has become a global threat
bull In 1993 WHO declared Tuberculosis a Global emergency
bull Animals shed the bacilli in Milk humanrsquos get infected after drinking the unsterilized Milk
bull Pasteurization has reduced the incidence of Bovine tuberculosis
DrTVRao MD 46
Why Tuberculosis continues to be Important
bull Someone in the world is newly infected with TB bacilli every second
bull Overall one-third of the worlds population is currently infected with the TB bacillus
bull 5-10 of people who are infected with TB bacilli (but who are not infected with HIV) become sick or infectious at some time during their life People with HIV and TB infection are much more likely to develop TB
DrTVRao MD 47
bull Programme Created by DrTVRao MD for Medical and Paramedical
Students in Developing world
bull Email
bull doctortvraogmailcom
DrTVRao MD 48
![Page 44: Diagnosis of tuberculosis an Update](https://reader031.fdocuments.in/reader031/viewer/2022032113/55a62b711a28abd5138b48bb/html5/thumbnails/44.jpg)
HIV Considerations
bull HIV is the strongest risk factor for progression to active disease
bull HIV kills CD4+ T Helper cells which normally inhibit M tuberculosis
bull HIV interferes with PPD skin test
bull Protease inhibitors interfere with rifampin
DrTVRao MD 44
Epidemiologybull An ancient disease called as white plague
bull 13 of the world population is infected
bull 2 billion infected
bull Each year 9 lakhs to 1 million are infected
bull Poor nations phase the burnt of the disease
bull In developing world gt 4o of the population is effected
bull 15 million suffer the disease
bull 3 million are highly infective
DrTVRao MD 45
MDR tuberculosis
bull Multidrug resistant tuberculosis has become a global threat
bull In 1993 WHO declared Tuberculosis a Global emergency
bull Animals shed the bacilli in Milk humanrsquos get infected after drinking the unsterilized Milk
bull Pasteurization has reduced the incidence of Bovine tuberculosis
DrTVRao MD 46
Why Tuberculosis continues to be Important
bull Someone in the world is newly infected with TB bacilli every second
bull Overall one-third of the worlds population is currently infected with the TB bacillus
bull 5-10 of people who are infected with TB bacilli (but who are not infected with HIV) become sick or infectious at some time during their life People with HIV and TB infection are much more likely to develop TB
DrTVRao MD 47
bull Programme Created by DrTVRao MD for Medical and Paramedical
Students in Developing world
bull Email
bull doctortvraogmailcom
DrTVRao MD 48
![Page 45: Diagnosis of tuberculosis an Update](https://reader031.fdocuments.in/reader031/viewer/2022032113/55a62b711a28abd5138b48bb/html5/thumbnails/45.jpg)
Epidemiologybull An ancient disease called as white plague
bull 13 of the world population is infected
bull 2 billion infected
bull Each year 9 lakhs to 1 million are infected
bull Poor nations phase the burnt of the disease
bull In developing world gt 4o of the population is effected
bull 15 million suffer the disease
bull 3 million are highly infective
DrTVRao MD 45
MDR tuberculosis
bull Multidrug resistant tuberculosis has become a global threat
bull In 1993 WHO declared Tuberculosis a Global emergency
bull Animals shed the bacilli in Milk humanrsquos get infected after drinking the unsterilized Milk
bull Pasteurization has reduced the incidence of Bovine tuberculosis
DrTVRao MD 46
Why Tuberculosis continues to be Important
bull Someone in the world is newly infected with TB bacilli every second
bull Overall one-third of the worlds population is currently infected with the TB bacillus
bull 5-10 of people who are infected with TB bacilli (but who are not infected with HIV) become sick or infectious at some time during their life People with HIV and TB infection are much more likely to develop TB
DrTVRao MD 47
bull Programme Created by DrTVRao MD for Medical and Paramedical
Students in Developing world
bull Email
bull doctortvraogmailcom
DrTVRao MD 48
![Page 46: Diagnosis of tuberculosis an Update](https://reader031.fdocuments.in/reader031/viewer/2022032113/55a62b711a28abd5138b48bb/html5/thumbnails/46.jpg)
MDR tuberculosis
bull Multidrug resistant tuberculosis has become a global threat
bull In 1993 WHO declared Tuberculosis a Global emergency
bull Animals shed the bacilli in Milk humanrsquos get infected after drinking the unsterilized Milk
bull Pasteurization has reduced the incidence of Bovine tuberculosis
DrTVRao MD 46
Why Tuberculosis continues to be Important
bull Someone in the world is newly infected with TB bacilli every second
bull Overall one-third of the worlds population is currently infected with the TB bacillus
bull 5-10 of people who are infected with TB bacilli (but who are not infected with HIV) become sick or infectious at some time during their life People with HIV and TB infection are much more likely to develop TB
DrTVRao MD 47
bull Programme Created by DrTVRao MD for Medical and Paramedical
Students in Developing world
bull Email
bull doctortvraogmailcom
DrTVRao MD 48
![Page 47: Diagnosis of tuberculosis an Update](https://reader031.fdocuments.in/reader031/viewer/2022032113/55a62b711a28abd5138b48bb/html5/thumbnails/47.jpg)
Why Tuberculosis continues to be Important
bull Someone in the world is newly infected with TB bacilli every second
bull Overall one-third of the worlds population is currently infected with the TB bacillus
bull 5-10 of people who are infected with TB bacilli (but who are not infected with HIV) become sick or infectious at some time during their life People with HIV and TB infection are much more likely to develop TB
DrTVRao MD 47
bull Programme Created by DrTVRao MD for Medical and Paramedical
Students in Developing world
bull Email
bull doctortvraogmailcom
DrTVRao MD 48
![Page 48: Diagnosis of tuberculosis an Update](https://reader031.fdocuments.in/reader031/viewer/2022032113/55a62b711a28abd5138b48bb/html5/thumbnails/48.jpg)
bull Programme Created by DrTVRao MD for Medical and Paramedical
Students in Developing world
bull Email
bull doctortvraogmailcom
DrTVRao MD 48