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What is the Gram and microscopic arrangement of both staph and micrococcus? |
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Gram +Cocci in clusters, pairs or tetrads |
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Are staph and micrococcus catalase positive or negative? |
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Positive |
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What sites of infection are staph infections associated with? |
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various skin and mucosal surfaces when strain gains entrance to normally sterile site |
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Is S. aureus coagulase negative or positive? |
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Positive |
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What are 3 diseases associated with Staph aureus? |
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Impetigo - skin infectionScalded skin syndrome - affects babiesToxic shock syndrome - systemic |
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What 3 species of Staph are assoc. with nosocomial infections other than S. aureus? |
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S. epidermidisS. haemolyticusS. lugdunenis |
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Are S. epidermidus, S. haemolyticus, and S. lugdunenis coag neg or pos? |
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negative |
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What two characteristics of S. epidermidis enhances its likelihood of infection? |
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Its production of an exopolysaccharide that enhances attachment and its ability to acquire resistance to most antimicrobial agents used in the hospital |
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How is S. lugdunensis differentiated from other coag neg staph from sterile sites? |
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PYR pos and pos for ornithine decarboxylase |
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Why does S. lugdunensis need to be differentiated from other coag neg staph from sterile sites? |
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Because it has different interpretative criteria for oxacillin |
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What infection is S. saprophyticus most commonly assoc. with? |
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community acquired urinary tract infections in young sexually active females |
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What media can be used to cultivate staph and micrococcus? |
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5% sheep blood agar, Chocolate agar, broth blood cultures, Nutrient broths |
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What selective media is used to isolate staph? |
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Mannitol salt agar |
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What would a colony with a yellow halo on an MSA plate indicate? |
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that it is a staph colony that can ferment mannitol |
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What are the incubation conditions to cultivate staph on BAP, chocolate and MSA? |
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BAP and Chocolate - 35oC in CO2 or ambient air from 24 hrMSA 48-72 hr |
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What is the cultural characteristics of S. aureus on BAP? |
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med - large colonies, smooth, slightly raised, translucent, creamy yellowBeta hemolytic! |
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What are the cultural characteristics of S. epidermidis on BAP? |
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small - med colonies, translucent, gray-white, non or alpha hemolytic, sticky (slime producing) |
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What are the cultural characteristics of S. saprophyticus? |
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large, glossy, opaque, convex, Usually white (can be yellow or orange) |
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What are the cultural characteristics of Micrococcus on BAP? |
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small - med, non-hemolytic, variety of pigments but usually yellow, opaque and convex |
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What is the efffect of Lysostaphin on micrococcus versus staph? |
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Micrococcus - no lysisStaph - lysis |
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Are micrococcus and staph resistant or susceptible to furazolidone? |
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Micrococcus - resistantStaph - susceptible |
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Are micrococcus and staph resistant or susceptible to and A disc? |
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Micrococcus - susceptibleStaph - resistant |
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What are the oxidase reactions of micrococcus and staph? |
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micrococcus - posstaph - neg |
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Are micrococcus and staph aerobic, anaerobic, facultatively anaerobic, or microaerophilic? |
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Micrococcus - aerobicStaph - facultatively anaerobic |
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What is staph aureus's DNA hydrolysis rxn? |
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S. aureus - positive |
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What are the two coagulase tests? |
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Rapid slide test and tube test |
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What does a positive rapid slide test indicate? |
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bound coagulase - clumping factor |
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what does a positive tube coagulase test indicate? |
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free coagulase - clotting factor |
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What is S. intermedius assoc with? |
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dog bite wound infections? |
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What is S. intermedius most often confused with? |
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S. aureus |
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What are the characteristics of S. intermedius? |
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white - yellow, creamy opaque coloniescatalase and coagulase pos |
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When should coag negative staph be identified to species? |
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For normally sterile sites, isolates from prosthetic devices or catheters, isolates from urinary tract infections |
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What serodiagnosis for staph can be done? |
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antibodies to teichoic acid - wall component of gram + bacteria |
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What antimicrobial susceptibilities might be run on Staph species? |
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penicillin - almost all resistantMethicillin, oxacillinVancomycin is alternative for resistant strainsDaptomycin may be done if MIC for Vancomycin is too high |
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What infections are micrococcus associated with and what antimicrobials is it susceptible to? |
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Rarely infects humansSusceptible to most beta-lactams = penicillin |
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