Download - Altamash classification & staphylococci

SYSTEMIC BACTERIOLOGYSYSTEMIC BACTERIOLOGY

CLASSIFICATION OF BACTERIACLASSIFICATION OF BACTERIA

TAXONOMY

Includes

• Classification

• Identification

• Nomenclature

• CLASSIFICATION

Is the arrangement of organisms into taxonomic groups on the basis of similarities or relationships (i.e. common properties).

• IDENTIFICATION:

Is the practical use of a classification scheme to : Isolate & identify the causative agent of a disease.

• NOMENCLATURE

Is naming of an organism by international rules according to its characteristics. Genera – Species – Sub species .

CLASSIFICATION OF CLASSIFICATION OF MEDICALLY IMPORTANT MEDICALLY IMPORTANT

BACTERIABACTERIA

•

BACTERIA

RIGID THICK-WALLED CELLS

FLEXIBLE, THIN-WALLEDCELLS

WALL-LESSCELLS


BACTERIABACTERIA

•


FREE LIVING (EXTRACELLULAR)

NON FREE LIVING(OBLIGATE INTRACELLULAR

PARASITES)

FREE LIVINGBACTERIA

GRAM POSITIVEBACTERIA

GRAM NEGATIVE BACTERIA

ACID-FASTBACTERIA

COCCI RODS

SPOREFORMING

NONSPOREFORMING

COCCI RODS

CLASSIFICATION OF MEDICALLY IMPORTANT BACTERIA

GRAM POSITIVE BACTERIA (COCCI/ RODS)

CHARACTERISTICS GENUS DISEASE

COCCI STAPHYLOCOCCI ABSCESS SKIN & OTHER ORGANS

STREPTOCOCCI PNEUMONIA, PHARYNGITIS

CELLULITIS

RODS (SPORE FORMING RODS/ NON SPORE FORMING RODS)

SPORE FORMING RODS (AEROBIC/ ANAEROBIC)

(a) AEROBIC BACILLUS ANTHRAX

(b)ANAEROBIC CLOSTRIDIA TETANUS

CLASSIFICATION OF MEDICALLY IMPORTANT BACTERIA

NON-SPORE FORMING

RODS

NON FILAMENTOUS CORYNEBACTERIUM DIPHTHERIA

LISTERIA MENINGITIS

FILAMENTOUS ACTINOMYCES ACTINOMYCOSIS

NOCARDIA NOCARDIOSIS

GRAM NEGATIVE BACTERIA (COCCI/RODS)

COCCI NEISSERIA GONORRHEA

MENINGITIS

GRAM NEGATIVE RODS FACULTATIVE RODS

(STRAIGHT/ CURVED)AEROBIC RODS ANAEROBIC

RODSCHARACTERISTICS GENUS DISEASE

STRAIGHT RODS (RESPIRATORY/ZOONOTIC/ENTERIC)

•RESPIRATORY

ORGANISMS

HAEMOPHILUS MENINGITIS

BORDETELLA WHOOPING COUGH

LEGIONELLA PNEUMONIA

•ZOONOTIC

ORGANISMS

BRUCELLA BRUCELLOSIS

CHARACTERISTIC GENUS DISEASE

ZOONOTIC FRANCISELLA TULAREMIA

PASTEURELLA CELLULITIS

YERSINIA PLAGUE

•ENTERIC & RELATED ORG.

ESCHERICHIA UTI, DIARRHEA

SALMONELLA ENTEROCOLITIS

TYPHOID

KLEBSIELLA PNEUMONIA

ENTEROBACTER UTI

CHARACTERISTC GENUS DISEASE

CURVED F. RODS CAMPYLOBACTER ENTROCOLITIS

HELICOBACTER GASTRITIS, PEPTIC ULC

VIBRIO CHOLERA

AEROBIC RODS PSEUDOMONAS UTI, PNEUMONIA

ANAEROBIC RODS

BACTEROIDES PERITONITIS

ACID FAST BACTERIA

MYCOBACTERIUM TB, LEPROSY


BACTERIABACTERIA

•


FREE LIVING (EXTRACELLULAR)

NON FREE LIVING(OBLIGATE INTRACELLULAR

PARASITES)

NON FREE LIVING (OBLIGATE INTRACELLULAR

PARASITES)

CHARACTERISTIC GENUS DISEASE

RICKETSSIA ROCKY MOUNTAIN SPOTTED FEVER

CHLAMYDIA URETHRITIS, TRACHOMA, PSITTACOSIS


BACTERIABACTERIA

•

BACTERIA


FLEXIBLE, THIN-WALLEDCELLS

WALL-LESSCELLS

FLEXIBLE, THIN WALLED CELLS (SPIROCHETES)

GENUS DISEASE

TREPONEMA SYPHILIS

BORRELIA LYME DISEASE

LEPTOSPIRA LEPTOSPIROSIS

WALL-LESS BACTERIA

GENUS DISEASE

MYCOPLASMA PNEUMONIA

DefinitionsDefinitions• Epidemiology

– The study of the transmission of disease

• Communicable Disease – A disease that can be transmitted from one individual to

another

• Contagious Disease – A communicable disease that is easily spread from one

individual to another

• Noncommunicable Disease – A disease that is not transmitted from one individual to

another

III. A.III. A. DefinitionsDefinitions

• Epidemic Disease– A disease condition present in a greater

than usual percentage of a specific population

• Pandemic Disease

• Endemic Disease– A disease condition that is normally found

in a certain percentage of a population

– An epidemic affecting a large geographical area; often on a global scale

III. A.III. A. DefinitionsDefinitions

• Reservoir of Infection – The source of an infectious agent

• Carrier– An individual who carries an infectious agent

without manifesting symptoms, yet who can transmit the agent to another individual

• Fomites– Any inanimate object capable of being an

intermediate in the indirect transmission of an infectious agent

III. A.III. A. DefinitionsDefinitions• Animal Vectors

– An animal (nonhuman) that can transmit an infectious agent to humans

– Two types: mechanical and biological • Biological animal vectors: The infectious agent must

incubate in the animal host as part of the agent’s developmental cycle; eg, the transmission of malaria by infected mosquitoes

• Mechanical animal vectors: The infectious agent is physically transmitted by the animal vector, but the agent does not incubate or grow in the animal; eg, the transmission of bacteria sticking to the feet of flies

GRAM POSITIVE COCCIGRAM POSITIVE COCCI

GENUS

• STAPHYLOCOCCI

• STREPTOCOCCI

GENERAL PROPERTIES

• NON MOTILE, NON SPORE-FORMING

• STAPHYLOCOCCI: CATALASE POSITIVE

IN CLUSTER

• STREPTOCOCCI : CATALASE NEGATIVE

IN CHAINS

STAPHYLOCOCCISTAPHYLOCOCCI

INTRODUCTIONINTRODUCTION

• Staphyloccocci - derived from Greek “stapyle” (bunch of grapes)

• Gram positive cocci arranged in clusters

• Hardy organisms surviving many non physiologic conditions

• Include a major human pathogen and skin commensals

Grouping for Clinical Grouping for Clinical PurposesPurposes

• 1. Coagulase positive Staphylococci– Staphylococcus aureus

• 2. Coagulase negative Staphylococci– Staphylococcus epidermidis– Staphylococcus saprophyticus

A. Staphylococcus aureusA. Staphylococcus aureus

• Major human pathogen

• Habitat - part of normal flora in some humans (nose , sometimes skin esp hospital staff and patients, vagina of 5% females) and animals

• Source of organism - can be infected human host, carrier, fomite or environment

DISEASESDISEASES

• Due to direct effect of organism– Local lesions of

skin– Deep abscesses– Systemic

infections

• Toxin mediated– Food poisoning– toxic shock

syndrome– Scalded skin

syndrome

IMPORTANT PROPERTIESIMPORTANT PROPERTIES• Gram positive cocci, arranged in

clusters

• Non spore forming, non motile

• Catalase positive (breaks H2O2 into O2 & H2O)

• S. aureus: Coagulase positive, Hemolytic, Ferments Mannitol.

• Plasmid mediated Antibiotic resistance in S. aureus

• Cell wall components of S. aureus

Cell wall components & antigens of Cell wall components & antigens of S.aureusS.aureus

• Protein A (binds to Fc portion of Ig G at complement binding site)

• Teichoic acid (adherence, antibody formation)

• Microcapsule (11 serotypes)

• Peptidoglycan has endotoxin-like properties.

Factors predisposing to S. Factors predisposing to S. aureus infectionsaureus infections

• Host factors

– Breach in skin– Chemotaxis defects– Opsonisation defects– Neutrophil functional

defects– Diabetes mellitus– Presence of foreign

bodies

• Pathogen Factors– Catalase (counteracts

host defences)– Coagulase– Hyaluronidase– Lipases (Imp. in

disseminating infection)

– B lactasamase(ass. With antibiotic resistance)

Factors predisposing to S. Factors predisposing to S. aureus infectionsaureus infections

• Toxins produced by S. aureus

• Enterotoxin

• Toxic shock syndrome toxin (TSST is a super antigen)

• Exfoliatin (epidermolytic)

• Leucocidins

• Alpha toxin (tissue necrosis)

• Staphylokinase

SKIN LESIONS (Pyogenic)SKIN LESIONS (Pyogenic)• Styes

• Furuncles(infection of hair follicle)

• Carbuncles (infection of several hair follicles)

• Wound infections(progressive appearance of swelling and pain in a surgical wound after about 2 days from the surgery)

• Impetigo(skin lesion with blisters that break and become covered with crusting exudate)

• Cellulitis

IMPETIGOIMPETIGO

SYMPTOMS OF STAPH SYMPTOMS OF STAPH INFECTIONSINFECTIONS

The symptoms of a staph infection depends on where the infection is. The staph bacteria can cause:

• Boils – an abscess, bump, or swelling within the skin. Also called a furuncle.

• Cellulitis – a “flat” skin infection which can make the skin red, painful and warm but does not have pustules.

• Folliculitis – an infection of the hair follicles

• Impetigo – pustules (bulbous impetigo) or honey colored crusted lesions on the skin

Staphylococcol Staphylococcol InfectionInfection

DEEP ABSCESSSESDEEP ABSCESSSES

• Can be single or multiple

• Breast abscess can occur in 1-3% of nursing mothers in puerperium

• Can produce mild to severe disease

• Other sites - kidney, brain from septic foci in blood

Systemic InfectionsSystemic Infections• 1. With obvious focus

– Osteomyelitis, septic arthritis

• 2. No obvious focus• heart (infective endocarditis)• Brain(brain abscesses)

• 3. Ass. With predisposing factors – multiple abscesses, septicaemia (IV

drug users)– Staphylococcal pneumonia (Post viral)

B. TOXIN MEDIATED B. TOXIN MEDIATED DISEASESDISEASES

• 1. Staphylococcal food poisoning– Due to production of entero toxins– Superantigen – IL-1 & 2– heat stable entero toxin acts on gut– produces severe vomiting, non bloody

diarrhea following a very short incubation period

– Resolves on its own within about 24 hours

2. Toxic shock syndrome2. Toxic shock syndrome• High fever, diarrhoea, shock and

erythematous skin rash which desquamate

• Mediated via ‘toxic shock syndrome toxin’– super antigen

• 10% mortality rate• ass. With young women using

tampones during menstruation & wound infection

3. Scalded skin syndrome3. Scalded skin syndrome

• Disease of young children• Mediated through minor

Staphylococcal infection by ‘epidermolytic toxin’ producing strains

• Mild erythema and blistering of skin followed by shedding of sheets of epidermis

• Children are otherwise healthy and most eventually recover

S. aureus -- Kawasaki S. aureus -- Kawasaki syndromesyndrome

• Unknown etiology

• Vasculitis of medium & small sized arteries.

• Strawberry tongue

DIAGNOSISDIAGNOSIS

• 1. In all pus forming lesions – Gram stain and culture of pus

• 2. In all systemic infections– Blood culture

• 3. In infections of other tissues– Culture of relevant tissue or exudate

DiagnosisDiagnosis

• Gram Stain: Gram positive cocci in clusters

• Yellowish colonies , b-hemolytic on Blood agar

• Catalase and coagulase positive

• Mannitol fermenter

Antibiotic sensitivity patternAntibiotic sensitivity pattern• Very variable and not predictable• Very imp. In Pt. Management• Mechanisms

– 1.B lactamase production - plasmid mediated• Has made S. aureus resistant to penicillin group of

antibiotics - 90% of S. aureus (Gp A)• B lactamase stable penicillins (cloxacillin, oxacillin,

methicillin) used

– 2. Alteration of penicillin binding proteins• (Chromosomal mediated)Vancomycin is the drug of choiceMRSA, NRSA, VISA

• Tested in lab using methicillin• Referred to as methicillin resistant S.

aureus (MRSA)• Emerging problem in the world• In Sri Lanka prevalence varies from 20-

40% in hospitals• Drug of choice - vancomycin• In Japan emergence of VIRSA (vancomycin

intermediate resistant S. aureus)• No effective antibiotics discovered -We

might have to discover

2. Staphylococcus 2. Staphylococcus epidermidisepidermidis

• Skin commensal• Has predilection for plastic material• Ass. With infection of IV lines, prosthetic

heart valves, shunts• Causes urinary tract infection in cathetarised

patients• Has variable ABS pattern , highly resistant• Treatment should be aided with ABST• Hospital acquired• Novobiocin sensitive

3. Stapylococcus 3. Stapylococcus saprophyticussaprophyticus

• Skin commensal

• Imp. Cause of UTI in sexually active young women

• Usually sensitive to wide range of antibiotics

GRAM POSITIVE COCCI

S. aureus hemolyticmannitol yellow

+ -Staphylococcus (Clusters) Streptococcus (pairs & chains)

Catalase

BETA: Bacitracin S.pyogenes (group A)

CAMP/ Hippurate S. agalactiae (group B)

HemolysisCoagulase

S. epidermidisnonhemolytic (usually)mannitol white

ALPHA: Optochin /Bile Solubility S. pneumoniae

GAMMA: Bile Esculin 6.5% NaCl Group D* Enterococcus

Bile Esculin 6.5% NaCl Group D* Non-Enterococcus

(*can also be alpha hemolytic)

Note: S. viridans is Is alpha hemolytic and negative for all the tests below below

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Summary Figure (Identification Scheme)