Pneumonia pathogens
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Transcript of Pneumonia pathogens
PNEUMONIAS PNEUMONIAS & LOWER RESPIRATORY & LOWER RESPIRATORY
TRACT INFECTIONSTRACT INFECTIONS
Infectious Disease Epidemiology SectionOffice of Public Health
Louisiana Dept of Health & Hospitals...Your Taxes at Work…
504-568-5005 *** 800-256-2748www.oph.dhh.louisiana.gov
Clinical Presentation: Lower respiratory Tract
Infection
Prodrome ±
Symptoms of upper respiratory tract infection: sore throat, rhinorrhea
Fever, chillsNausea, vomiting, diarrheaHeadache, dizziness
Clinical Presentation: Lower respiratory Tract Infection
Acute Infection: Fever, chills Back pain, myalgias, arthralgias Headache, malaise, chills Nausea, vomiting
Chest Infection: Cough Chest pain Rales, wheezing, noisy chest
Characteristic changes on chest x-rays Increasing respiratory distress, may require
mechanical ventilation
Diagnostic etiology of pneumonia
About 40-60% of persons with pneumonia do not have a defined etiology…even after extensive testing for known respiratory pathogens
Community Acquired Pneumonia
Age-specific rates of hospital admission for community-acquired pneumonia caused by S. pneumoniae, M. pneumoniae, C. pneumoniae, or Legionella species
PneumoniaAcute Respiratory Disease &
Fever
Plague Tularemia
RICIN toxinStaphylococcal Enterotoxin B
TBLegionella
SARS
S.pneumo
PneumoniaAcute Respiratory Disease &
Fever
• They all look alike, sound alike• Not easy to differentiate from
other pneumonias• Bronchoscopy, sputum, bronchial
lavage…• Blood culture• Look for antibodies in serum
Pneumococci
Pneumococci
colonizes the upper respiratory tract cause:
disseminated invasive infections - bacteremia - meningitis
pneumonia & other lower respiratory tract infections
upper respiratory tract infections - otitis media - sinusitis
Risk Factors/ Increased risk for developing pneumococcal infection or
experiencing severe disease and complications
Children < 2 & adults aged > 65 years
Underlying medical conditions chronic cardiovascular diseases (CHF/
cardiomyopathy) chronic pulmonary diseases (COPD or
emphysema) chronic liver diseases (cirrhosis) Diabetes mellitus with CV or renal dysfunction Chronic renal failure or nephrotic syndrome Asthma NO unless with chronic bronchitis…
Risk Factors/ Increased risk for developing pneumococcal infection or
experiencing severe disease and complications
Asplenia Functional or anatomic (SCD or splenectomy) clearance of encapsulated bacteria from the bloodstream
decreased responsiveness to polysaccharide antigens as in immunosuppressive conditions
Immunosuppressive conditions:AIDS, CIDS, leukemia, lymphoma, multiple myeloma, Hodgkins disease, or generalized malignancy, organ or bone marrow transplantation; rx with alkylating agents, antimetabolites, or systemic corticosteroids
Pneumonia in HIV
Most common bacterial cause of pneumonia in HIV
Invasive pneumococcal disease often first clinical manifestation of children HIV
AIDS: annual attack rate of pneumococcal bacteremia ~ 1%
Pneumococcal Vaccine
Pneumovax-Merck and Pneu-Immune® 23 Lederle
include 23 purified capsular polysaccharide antigens serotype-specific antibody develops within 2-3
weeks in >80% of healthy young adults responses not consistent among 23 serotypes immunocompromised patients & children aged
< 2 whose immune systems are immature: antibody responses
Pneumococcal Vaccine
Effectiveness against invasive disease: 56% to 81% in case-
control studies not effective for prevention of common upper
respiratory diseases (e.g., sinusitis in children) efficacy for non-bacteremic pneumonia was not
demonstrated in elderly or in persons with chronic medical conditions
Side effects mild, local (pain at site, erythema, swelling), < 48
hrs, systemic reactions (fever, myalgias) severe local
reactions rare
Legionella
Legionnaires Disease
58th annual convention of the American Legion’s Pennsylvania Department at Bellevue Stanford Hotel in Philadelphia, July 21-24 1976
Starting July 22 - convention attendees and others who entered hotel became sick: pneumonia
182 hotel cases + 39 neighborhood cases 34 deathsSix months later a small bacterium named Legionella
pneumophila isolated from guinea pigs inoculated with the lung tissues of the cases
Legionnaires Disease
Similar agents isolated before but never before so thoroughly characterized
1943 L. micdadei from blood of febrile soldier in Fort Bragg, NC
in 1959 L.bozemannii from lung tissue of scuba diver
identified as the causative for Pontiac fever retrospectively by serology outbreak of acute febrile illness, 1968, MI DOH
building in Pontiac
Bacteriology
Legionellasmall (0.3 - 0.9 ) bacteria
~ very small Gram neg bacteriagrows on buffered charcoal yeast extract agar (BCYE) supplemented by
antibiotics to prevent overgrowth of Legionella dye to give Legionella a distinctive color
grows slowly, 3-5 days to have small colonies
Bacteriology
Legionella pneumophila multiplying inside a cultured human lung fibroblast
18 species
Legionella pneumophila serogroup 1 is the predominant species in USA
Bacteriology
in nature, infect free living amebae as Acanthamoeba, Naegleria and Harmanella multiply within amebae
do not colonize respiratory tractphagocytized by the macrophages, then
multiply within macrophagescell surface protein, macrophage infectivity
potentiator (Mip) necessary for invasion of phagocytes and expression of virulence
mutation in the Mip gene increase virulence 80-fold
Natural Habitat
Occurs worldwidepreferred habitat: WATERpreferably WARM WATERS with scale, sediment, metallic ions and commensal florawell adapted to hot water distribution system in
dwellings: colonizes hot water heaters, storage tanks, pipes, shower heads, plumbing materials, faucet aerators, AC cooling towers, evaporative condensers
found in 1-30% of home hot water systemsmultiplies in free living amebae: Acanthamoeba, Naegleria..
Transmission
Inhalation of aerosols of water contaminated with Legionella
primary mechanism of entry: aerosols generated by cooling towers, showers, faucets, respiratory therapy equipment and room-air humidifiers
aspiration of contaminated potable water also proposed
NO Person-to-person transmission
Epidemiology
Incubation 2-10 days
80% of reported cases are SPORADIC
Outbreaks in hospitals, cruise ships, hotels and other large buildings
Clinical: Pneumonia
Common cause of PNEUMONIA% community acquired pneumonias due
to Legionella is difficult to estimate diagnostic tests for recent Legionella not
routineretrospective & prospective studies
1%-5% CAP pneumonias depending on geographic setting
risk higher among cigarette smokers, elderlies, immunocompromised or chronically ill individuals
Clinical
wide range of clinical responseasymptomatic serologic conversion
self limited febrile illness (Pontiac fever) headache, chills myalgias or progressive
severe pneumonia (Legionnaire’s disease)Legionnaire’s disease cannot be distinguished clinically or radiologically from other pneumonias
Diagnosis
Isolation of Legionella from respiratory secretion cultures
Visualization of Legionella in respiratory secretions or tissue by immunofluorescence
Detection of Legionella serogroup 1 antigen in the urine by radioimmunoassay, or enzyme immunoassay (EIA) more sensitive and specific than IF on
respiratory tract secretions rapid diagnosis but only detects infection due to this species
and serogroup
Diagnosis
Four fold rise in antibody titer to Legionella
rising to above 1:128 in paired seraAntibodies to Mycoplasma
pneumoniae, Campylobacter jejuni, Pseudomonas aeruginosa and Bacteroides fragilis, may cause false-positive IFA test results
Diagnosis
One elevated antibody titer does NOT confirm case of
recent legionellosis
1% - 16% of adults have IFA titers 1:256
Safe Water ”ways”
grows poorly at < 20 C and > 50 C
killed at temperatures > 60 Csusceptible to
chlorine and bromine disinfectants ozone heavy metal ions UV
studies performed under lab conditions not always successful in predicting effectiveness under field conditions
Safe Water ”ways”
Cooling towers and evaporative condensers disinfected by hyperchlorination safer approaches would be to
place them away from public areas
to use drift eliminators to clean from organic matter
periodically to dose automatically with a
biocide
Cooling Tower
Safe Water ”ways”
Whirlpool spas halogen levels at 4 - 10 mg/L,
monitor frequently pH at 7.2 - 7.8 drain and clean system frequently replace filters regularly
Safe Water”ways”
Hot water system flushing for >5mn at > 65 C hyperchlorination (flushing with water 10
mg/L free residual chlorine) may grow back unless
• hot water maintained at 50 C • cold water at 20 C • residual chlorine at 1-2 mg/L of free chlorine• risk of scalding users• hyperchlorination causes corrosion• remove scale and sediments• UV, ozone and heavy metals +
Pertussis
Bacteriology
Bordetella pertussis fastidious Gram negBordet Gengou agar
with 15% sheep blood or Regan Lowe
Swabs to be inoculated immediately
Delays isolation incubated at 35 C, in
moist airGrowth 5 days
Transmission
Without immunity, susceptibility = 100%, no child escaped pertussis Household exposure: attack rate
pertussis = 90% to 100%, (in school 50%) mumps = 31% measles=75% chickenpox=61%
Humans Humans onlyonly
large droplets from upper
respiratory tract NOT by droplet
nuclei or fomites Asymptomatic
cases exist, role ??
Period of Communicability
Incubation7d (6-25 d)
CATHARRHAL10-14d
CommunicabilityOnset + 21 d
Exposed HCW: ex+6 until +21 or rx+5d
Infected HCW: Onset +21 or Rx+5d
PAROXYSMAL7-14d Convale
scenceweeks
Epidemiology: before Vaccine
endemic with epidemics at 3 - 5 years interval in unimmunized population
majority among children 40% among infants < months 75% among children < 5
years of age incidence rate of
whooping cough was about 150 /100,000 /year
distributed worldwideoutbreaks any time, slightly more during
summer & early fall
Epidemiology After Vaccine
Immunization or immunity after disease prevents disease but NOT infection
US rates down to 0.5 - 1 /100,000/yr
nowadays resurgence pertussis = epidemic with 2 - 5 years cycles immunization cases but did not change
cycles
Epidemiology After Vaccine
Common among adults
IgA antibodies only produced after a natural infection, not after immunization
Prevalence of IgA antibodies similar among adults in countries with generalized immunization (USA) or in countries with no systematic pertussis immunization (Germany in the 1970s): vaccine did not prevent production of IgAVaccine did not prevent transmission
25% of adults with persistent cough have serologic evidence of recent pertussis infection
Pertussis in the USA
Log scal
e
Pertussis in the USA
Clinical
first week: catarrhal phase: cough increases
paroxysmal stage lasts for 3-4 weeks: starts after 2 weeks severe spells of coughing typical whoop: The whoop
created by vigorous inspiration through the
glottis at end of paroxysm during paroxysms, the child
may turn blue or vomit fever usually low subconjunctival, cerebral
and nose hemorrhages
Mortality
related to age: 50% in young infants negligible after 5
pulmonary complications
Encephalopathy
otitis media, mastoiditis, inanition and diarrhea are common in developing countries
permanent neurological
Diagnosisnasopharyngeal culture
nasopharyngeal mucus collected on Dacron or calcium alginate swab
then inoculated on special culture media Bordet Gengou agar
with sheep’s blood Regan-Lowe medium
Stuart’s transport medium if delay
culture + from beginning of catarrhal stage+ 3 weeks
a whooping cough syndrome similar to pertussisBordetella parapertussis, Chlamydia trachomatis adenoviruses
Direct ImmunoFluorescence Assay (DFA) not as specific or as sensitive as culture
Prevention: Early Case Finding
EARLY DETECTION essential to institute prevention
Mild upper respiratory infection mild fever + coughing > 1 week duration SUSPECT PERTUSSIS
Prevention: Contact Investigation
identify individuals at risk, evaluate immunization status
implement isolation and chemoprophylaxismonitor for respiratory for 14 days after
contact brokenhousehold and other close contacts
irrespective of their immunization status: erythromycin po (40 to 50 mg/kg/day in 4 divided
doses, maximum 2 g) for 14 days eliminates carriage, may prevent disease if early immune are protected against new disease but
not against infection and serve as transmitters compliance poor 5 day azithromycin, or 7 day clarithromycin OK Trimethoprim-Sulfamethoxazole alternate
Prevention: Day Care Centers
immunization as appropriate and chemoprophylaxis:
same doses as the household contacts
symptomatic children excluded pending medical evaluation: children on
chemoprophylaxis may return 5 days after initiation of erythromycin
Childhood Immunization Childhood Immunization ScheduleSchedule
Birth 1m 2m 3m 4m 6m 12m 15m 18m 4-6y 11-12y Birth 1m 2m 3m 4m 6m 12m 15m 18m 4-6y 11-12y
HBV3
DTP
HBV1HBV2
DTPDTP DTP
HibHib
Hib Hib
Polio Polio Polio
MMR MMR or MMR
VaricellaVaricella VaricellVaricellaa
Pertussis Vaccine
Whole cell vaccinesAcellular vaccines:
5 immunogenic components capable individually or combined, of producing immunity
acellular DPT vaccines initially developed in Japan
inactive form of pertussis toxin, filamentous hemagglutinin, agglutinogens, outer membrane protein
use of acellular vaccine reduces side effects: fever & irritability
USA: acellular vaccines combined with DT recommended
Prevention: Isolation /Exclusion
Health Care Worker1-suspected HCW : removed from patient contact until
status determined2-infectedHCW: + culture even if asymptomatic)
removed from direct patient contact from onset to 21 days or until 7 days after rx start
3-exposed HCW: asymptomatic and neg cultures can continue
Isolation of the hospital patientDroplet precautions until onset+21d
or rx+7dExclusion from school & day care
Prevention in Health Care Facilities: Triage
Questions patients with fever and respiratory symptoms
Triage at first points of contact or before performing history-taking or examinations
Surgical mask on suspect patients early during the
triage process