MCRO 423 Study Guide - Final Guide: Klebsiella Pneumoniae, Shiga Toxin, Diphtheria Toxin

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Staphylococcus: gram (+), catalase (+), skin/mucous membranes, endogenous infections. Lab diagnostic: msa (mannitol salt agar): high salt inhibits most but staph. Mannitol turns it pink yellow: tg agar: tellurite reduction forms shiny black colonies, coagulase: formation of clots, agglutination test (staphytex): antigens on latex beads clump if s. aureus is present. Staph species: s. aureus, s. epidermidis, s. saprophyticus, s. lugdunensis. Exfoliating toxin (eta & etb): serine proteases, causes skin to slough off, staphylococcal scalded skin syndrome (ssss). Cutaneous infections: impetigo (pus pockets on face), folliculitis (inflam. of hair follicle), carbuncle (localized boil goes deeper into tissue) Systemic infections: pneumonia, meningitis, osteomyelitis, septic arthritis, acute endocarditis. Staphylococcus lugdunensis: most common cause of valve endocarditis in native hearts. Treatment of s. aureus: less than 10% are susceptible to penicillin. Normal penicillin binding protein is targeted by antibiotics but this one has a much lower affinity. Streptococcus: gram (+), catalase (-), oxidase (-), non-motile, (-) for nitrate reduction, microaerophiles and fac anaerobe.