Staphylococcus aureus = majorStaphpathogen 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 oftenPenicillin G resistant Other UniqueFeatures- thermonstable nucleus (+) - cells divides perpendicular to last plane of division -Ribitolin teichoic acid - high salt tolerance (e.g. can grow on salted meats) -can ferment mannitolorganic acids -longstationary phase other Staph are thermostable (-) Virulence FactorsProtective-protein A(binds IgGto prevent phago/ops)- coagulase (fibrinformation,αphago)- hemolysins - leukocidins- penicillinaseTissue-destroying - hyaluronidase (breaks down proteog in CT) - staphylokinase (lyses formed fibrin clots) - lipase (disseminate)-clumping factor (adhere to fibrinogen,αuptake) Host defense mechanisms include: skin, group IIA phospholipase A (from platelets), PMN-C3 opsonization & Ab to toxins -αhemolysin forms pores (most potent), ßlysis - leukocidinPMN lysis + LT4 + IL-8inflamm -Exfoliative exotoxinscalded skin syndrome -Enterotoxin (SE)food poisoning, superAg -TSST-1IL1B +TNFTSS, agr-quorum sensing hemolysins & leukocidin lyse cells by creating pores in the membrane Associated DiseasesExotoxin-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) -Vancomycinif Methicillin-resistant (MRSA) -Clindamycin no protective immunity; infxn can be aquired over & overGram stain under microscope Culture on blood agar
Staphylococcus saprophyticus Lab IDG+ grape-like clusterscatalase(+)coagulase(-)all Staph = cat(+)all Strep = cat(-)Metabolism- facultative w/ ETCOther UniqueFeatures- thermostable nucleus (-)- cells divide perpendicular to last place of division-Glycerolin teichoic acid-cannotferment mannitol - “γhemolysis” on blood agar Virulence Factors Associated Diseases*UTI - causes 10-20% of 1°UTIs in young♀ - 90% are symptomatic Treatment(s)-Penicillin -Novobiocinresistant compare S. epidermidisStaphylococcus epidermidis N = nosocomial pathogen & most common isolate of coagulase(-)Staph Lab IDG+ grape-like clusters catalase(+) coagulase(-) all Staph = cat(+) all Strep = cat(-) Metabolism- facultative w/ETC Other UniqueFeatures- thermostable nucleus (-) - cells divide perpendicular to last plane of division -Glycerol
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