MICROcardsBACTERIArevisedARA1 - -Cellulitis abscess...

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Staphylococcus aureus = major Staph pathogen aureus = gold Lab ID G+ grape-like clusters catalase(+) coagulase(+) golden-yellow pigment (from carotenoids) all Staph = cat(+) all Strep = cat(-) S. aureus is only Staph that is coagulase (+) Metabolism - facultative w/ ETC often Penicillin G resistant Other Unique Features - thermostable nucleus (+) - cells divides perpendicular to last plane of division - Ribitol in teichoic acid - high salt tolerance (e.g. can grow on salted meats) - can ferment mannitol organic acids - long stationary phase other Staph are thermostable (-) Virulence Factors Protective - protein A (binds IgG to prevent phago/ ops) - coagulase (fibrin formation, α phago) - hemolysins - leukocidins - penicillinase Tissue-destroying - hyaluronidase (breaks down proteog in CT) - staphylokinase (lyses formed fibrin clots) - lipase (disseminate) -clumping factor (adhere to fibrinogen, α uptake) Host defense mechanisms include: skin, group IIA phospholipase A (from platelets), PMN-C3 opsonization & Ab to toxins - α hemolysin forms pores (most potent), ß lysis - leukocidin PMN lysis + LT 4 + IL-8 inflamm - Exfoliative exotoxin scalded skin syndrome - Enterotoxin (SE) food poisoning, superAg - TSST-1 IL1B +TNF TSS, agr-quorum sensing hemolysins & leukocidin lyse cells by creating pores in the membrane Associated Diseases Exotoxin-dependent * Gastroenteritis (“food poisoning”) * Toxic Shock Syndrome (can be lethal!) - high fever, nausea & vomiting, watery diarrhea - erythematous rash, HoTN - desquamation of palms & soles (late) * Scalded Skin Syndrome , Bullous Impetigo NOT normal flora, but transiently colonizes nasopharynx of ~30% pop. can colonize -Cellulitis, abscess, furuncle, carbuncle, wound inf. Direct Invasion (tend to be localized) * Pneumonia * Meningitis * Osteomyelitis (boys <12) * Acute bacterial endocarditis – rapid veg growth * Bacteremia/sepsis, Septic arthritis – synovial fluid * Skin: folliculitis, carbuncles, abscesses, cellulitis * UTI nasopharynx, skin, vagina risk in medical personnel, diabetics & IV drug users Diagnosis - Culture - PCR detection of ribosomal RNA MRSA! Treatment(s) - penicilinase-resistant penicillins (e.g. Methicillin ) - Vancomycin if Methicillin-resistant (MRSA) - Clindamycin no protective immunity; infxn can be aquired over & over
Early onset (<5d) ALL capsule types Late onset (5-30 d) Capsule type I I I mostly (70-80%) More to come next quarter More to come next quarter More to come next quarter More to come next quarter More to come next quarter More to come next quarter More to come next quarter More to come next quarter More to come next quarter More to come next quarter mediate attachment More to come next quarter More to come next quarter More to come next quarter Gram stain under microscope Culture on blood agar
Staphylococcus saprophyticus Lab ID G+ grape-like clusters catalase(+) coagulase(-) all Staph = cat(+) all Strep = cat(-) Metabolism - facultative w/ ETC Other Unique Features - thermostable nucleus (-) - cells divide perpendicular to last place of division - Glycerol in teichoic acid - cannot ferment mannitol - “ γ hemolysis” on blood agar Virulence Factors Associated

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