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Unformatted text preview: 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 - thermonstable 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-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 NOT normal flora, but transiently colonizes nasopharynx of ~30% pop. can colonize 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 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 Diseases * UTI- causes 10-20% of 1 ° UTIs in young ♀- 90% are symptomatic Treatment(s) - Penicillin - Novobiocin resistant compare S. epidermidis Staphylococcus epidermidis N = nosocomial pathogen & most common isolate of coagulase(-) Staph Lab ID G+ grape-like clusters...
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This note was uploaded on 09/14/2011 for the course PHARM mb taught by Professor Staff during the Spring '11 term at UCSD.
- Spring '11