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Pyogenic Coccus Pyogenic Coccus

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Staphylococci The Staphylococci

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Morphology & Identification Gram positive Facultative anaerobes Grape like-clusters Catalase positive Major components of normal flora skin nose

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Gram Positive cocci - staphylococci Pus

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Catalase test (-) (+)

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Pathogenesis & Immunity of Staphylococcus aureus

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Antigenic Structure

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Protein A inhibits phagocytosis Protein A immunoglobulin Fc receptor BACTERIUM PHAGOCYTE

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Toxins & Enzymes Catalase Coagulase ipaseHyaluronidase and L ipase sphingomyelinase CHemolysin or sphingomyelinase C Leukocidin Exfoliative Toxin Toxic Shock Syndrome Toxin (superantigen) Enterotoxins

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Pathogenesis

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Pathogenesis of staphylococcal infections Stye: Carbuncle: Impetigo

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Infections associated with indwelling devices

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Superantigens and the non-specific stimulation of T cells

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Clinical Findings- Clinical Findings- Suppurative A. (Skin)A. (Skin) Furuncle; Protein A, Leukocidin, Hemolysin Furuncle; Protein A, Leukocidin, Hemolysin Stye; lipase Stye; lipase Impetigo; contagious Impetigo; contagious Epidermal necrolysis Epidermal necrolysis Exfoliative Dermatitis (6,7,8); Exfoliative toxin Exfoliative Dermatitis (6,7,8); Exfoliative toxin Mastitis Mastitis Abscess (deep tissue); granulation; coagulase, hyaluronidase (burn, wound) Abscess (deep tissue); granulation; coagulase, hyaluronidase (burn, wound) B. Systemic : Bactermia (from abscess, wound, burn), Osteomyelitis (tibia),PneumoniaB. Systemic : Bactermia (from abscess, wound, burn), Osteomyelitis (tibia),Pneumonia

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Clinical Findings- Food poisoning not a human infectionnot a human infection food contaminated from humansfood contaminated from humans growth enterotoxin onset and recovery both occur within few hoursonset and recovery both occur within few hours Vomiting/ nausea/ diarrhea/ abdominal /painVomiting/ nausea/ diarrhea/ abdominal /pain

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Toxic shock syndrome feverfever scarlatinifor m rashscarlatinifor m rash desquamatio ndesquamatio n vomitingvomiting diarrheadiarrhea myalgiasmyalgias

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S. aureus babiesbabies scalded skin syndrome *exfoliatin

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Pseudomembranous Colitis

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Laboratory A. Direct examination; Gram Stain B. Primary media; BAP C. Differential Tests. 1.Mannitol Salts 2.Coagulase 3.DNase D. Phage typing E. Antibiotic Sensitivity (plasmid, B lactamase) penicillin /methicillin/vancomycin

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S. aureus on BAP

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Mannitol Salt Agar

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DNase test 0.1% Toluidine blue O (+): Pink 1N HCl (+) :

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S. aureus on potassium tellurite agar

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Lysostaphin test Staphylococcus Micrococcus

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API STAPH Kit

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Staphylococcus epidermidis major component skin floramajor component skin flora opportunistic infections opportunistic infections less common than S.aureus nosocomial infections nosocomial infections heart valves IdentificationIdentification Non-hemolytic ( sheep blood agar) Does not ferment mannitol Non-pigmented Coagulase-negative

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Staphylococcus saprophyticus urinary tract infections coagulase-negative not differentiated from S. epidermidis

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The Streptococcus

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Streptococcus

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Morphology & Identification facultative anaerobefacultative anaerobe Gram-positiveGram-positive Chains or pairsChains or pairs Catalase negativeCatalase negative (staphylococci are catalase positive) (staphylococci are catalase positive)

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Cell surface structure of S pyogenes and extracellular substances

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S. pyogenes fibronectin lipoteichoic acid F-protein epithelial cells

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M protein major targetmajor target natural immunity strain variationstrain variation antigenicity re-infectionre-infection occurs with different strain

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M protein fibrinogen rr r peptidoglycan rr r IgG Complement IMMUNE NON-IMMUNE

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Capsules Anti-phagocyticAnti-phagocytic mucoid strains

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Streptococci Lancefield groups Lancefield groups *one or more species per group *surface antigens

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streptococci groupable streptococci A, B and DA, B and D most important C, G, FC, G, F rare

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Non-groupable S. pneumoniaeS. pneumoniae pneumonia viridans streptococciviridans streptococci e.g. S. mutans *dental caries

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Toxins & Enzymes

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Hemolysis alpha beta gamma

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Classofication of Streptococci of Particular Medical Interest

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Pathogenesis of S pyogenes infections.

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Group A streptococcal infections affect all ages peak incidence at 5-15 years of ageGroup A streptococcal infections affect all ages peak incidence at 5-15 years of age

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. pyogenes -suppurative S. pyogenes -suppurative non-invasivenon-invasive pharyngitis skin infection, impetigo invasive bacteremiainvasive bacteremia toxic shock-like syndrome "flesh eating" bacteria pyrogenic toxin

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Pyrogenic toxin superantigensuperantigen T cell mitogen T cell mitogen activates immune systemactivates immune system

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Scarlet fever rash rash erythrogenic toxin erythrogenic toxin

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non-suppurative rheumatic fever inflammatory disease life threatening chronic sequalae feverfever heartheart joints joints rheumatic NOT rheumatoid arthritisrheumatic NOT rheumatoid arthritis

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Rheumatic fever -etiology M protein cross-reacts heart myosin autoimmunity cell wall antigens poorly digested in vivo persist indefinitely

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Rheumatic fever

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Acute glomerulonephritis immune complex disease of kidney immune complex disease of kidney

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Group B streptococcus neonatal meningitisneonatal meningitis septicemiasepticemia transmissiontransmission vaginal flora

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Group B streptococcus - identification hemolysis hemolysis hippurate hydrolysishippurate hydrolysis CAMP reactionCAMP reaction increases hemolysis of S. aureus

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Group D streptococcus Growth on bile esculin agarGrowth on bile esculin agar black precipitate 6.5% saline6.5% saline grow grow enterococci no growthno growth non-enterococci

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Enterococci distantly related to other streptococcidistantly related to other streptococci genus Enterococcusgenus Enterococcus gut floragut flora urinary tract infection fecal contaminationfecal contamination opportunistic infections particularly endocarditisparticularly endocarditis most common E. (S.) faecalismost common E. (S.) faecalis

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Enterococci resistant to many antibioticsresistant to many antibiotics including vancomycin terminal D-ala replaced by D-lactateterminal D-ala replaced by D-lactate

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Viridans streptococci diverse speciesdiverse species oraloral dental cariesdental caries hemolytic and negative for other tests hemolytic and negative for other tests non-groupable.non-groupable. includes S. mutansincludes S. mutans endocarditis tooth extraction

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Diagnostic Laboratory Test

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Post-infectious diagnosis (serology) antibodies to streptolysin Oantibodies to streptolysin O important if delayed clinical sequelae occur important if delayed clinical sequelae occur

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M T R R Serotyping

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S. pneumoniae - diplococci

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Virulence factors S. pneumoniae Virulence factors a. capsule: It is antiphagocytic, inhibiting entrapment and phagocytosis where type-specific opsonic antibody is absent. Non-capsulate mutants are avirulent in experimental animals.a. capsule: It is antiphagocytic, inhibiting entrapment and phagocytosis where type-specific opsonic antibody is absent. Non-capsulate mutants are avirulent in experimental animals. b. pneumolysin: It suppresses phagocytic oxidative burst. It is a membrane-damaging toxin. Thus it can destroys red blood cells and possibly ciliated epithelial cells.b. pneumolysin: It suppresses phagocytic oxidative burst. It is a membrane-damaging toxin. Thus it can destroys red blood cells and possibly ciliated epithelial cells. c. Surface protein adhesinand secretory IgA protease: The biologic effects are to help S.pneumoniae for the colonization and migration.c. Surface protein adhesinand secretory IgA protease: The biologic effects are to help S.pneumoniae for the colonization and migration. d.Teichoic acid and the Peptidoglycan fragment, phosphorylchorine : They can mediate the mobilization of inflammatory cells to the focus of infection and cause the tissue destruction/complement activationd.Teichoic acid and the Peptidoglycan fragment, phosphorylchorine : They can mediate the mobilization of inflammatory cells to the focus of infection and cause the tissue destruction/complement activation

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Capsule prominentprominent virulent strains anti-phagocyticanti-phagocytic carbohydrate antigenscarbohydrate antigens vary among strains immunityimmunity serotype specific vaccine contains multiple serotypesvaccine contains multiple serotypes only for susceptible populationonly for susceptible population

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clinic finding leading cause pneumonialeading cause pneumonia particularly young and old after damage to upper respiratory tract * e.g. following viral infection bacteremiabacteremia meningitismeningitis middle ear infections (otitis media)middle ear infections (otitis media)

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(Bile solubility test) (-) (+)

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Autolysis - identification Bile peptidoglycan cellmembrane lipoteichoic acid teichoic acid -choline autolysin

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Not optochin sensitive optochin sensitiveIdentification

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Quellung reaction using antiserausing antisera capsule "fixed" capsule "fixed" visible microscopically visible microscopically

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Streptex antiserum

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Latex agglutination - streptococci

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Prevention and Treatment Immunity ; 14 capsule types mixed vaccineImmunity ; 14 capsule types mixed vaccine Most strains susceptible to penicillin, but resistance is commonMost strains susceptible to penicillin, but resistance is common

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NEISSERIA Neisseria gonorrhoeae

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Gram negative Gram negative diplococci (pairs of cocci) diplococci (pairs of cocci) oxidase positive oxidase positive culture culture Thayer Martin. Thayer Martin. selective chocolate agar * heated blood (brown) Neisseria Neisseria

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Capsule LPS N. meningitidis Virulence Factors Similar, but Differences in utilization Hemolysin IgA protease PILI Opacity (OPA) proteins Outer Membrane Proteins N. gonorrhoeae LPS PILI Opacity (OPA) proteins Outer Membrane Proteins IgA protease NO capsule NO hemolysin X

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After 2-14 days After 2-14 days Found only in manFound only in man Gonorrhea: second most common venereal disease Gonorrhea: second most common venereal disease N. gonorrhoeae the "gonococcus"

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Neisseria gonorrhoeae Using the Gram stain in patient specimens, the organisms are most often observed in polymorphonuclear leukocytes Gram stain of pure cultureUrethral exudate

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Neisseria gonorrhoeae

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Pili = key in anchorage of organisms to mucosal epithelium. Nonpiliated gonococci are avirulent Porin proteins (Por) = prevent phagolysosome fusion & allow intracellular survival [ also called protein I] Opacity proteins (Opa) = binding of organisms to epithelium [also called protein II] Reduction-modifiable proteins (Rmp) = protection against bactericidal antibodies [ also called protein III] Neisseria gonorrhoeae OUTER MEMBRANE PROTEINS

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Neisseria gonorrhoeae Symptomatic infections are notably PURULENT Urethritis

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Neisseria gonorrhoeae Symptomatic infections are notably PURULENT Bartholins Duct

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Neisseria gonorrhoeae Purulent conjunctivitis Ophthalmia neonatorum Infection in newborns during vaginal delivery

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Neisseria gonorrhoeae Disseminated gonococcal infection (DGI). Fever, polyarthritis (or monoarticular septic arthritis), and/or dermatitis (pustules on a hemorrhagic base).

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Smear polymorphonuclear cellpolymorphonuclear cell Gram negative cocciGram negative cocci many in cells many in cells CultureCulture

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lactamase-resistant cephalosporin e.g. ceftriaxone resistant strains resistant strains common produce lactamases destroy penicillin Antibiotic therapy

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N. meningitidis N. meningitidis (the "meningococcus")

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N. meningitidis resides in man only usually sporadic cases usually sporadic cases mostly young children outbreaks outbreaks adults crowded conditions *e.g. army barracks

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Neisseria meningitidis upper respiratory tractinfection upper respiratory tract infection adhesion pili bloodstream bloodstream brain

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Meningococcal meninigitis 1-4 days 1-4 days Second most common meningitis Second most common meningitis pneumococcus, most common Fatal if untreated Fatal if untreated Responds well to antibiotic therapy Responds well to antibiotic therapy penicillin

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Laboratory Diagnosis spinal fluidspinal fluid Gram negative diplococci within polymorphonuclear cells within polymorphonuclear cells meningococcal antigens Culture Culture Thayer Martin agar

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Prevention - Capsule capsulecapsule inhibit phagocytosis anti-capsular antibodies anti-capsular antibodies stop infection antigenic variationantigenic variation serogroups vaccine vaccine multiple serogroups