Staphylococcus And Micrococcus

35 cards

Staphylococcus And Micrococcus Epidemiology, Morphology, Culture Characteristics, Diagnostic Biochemical Tests And Serology.

Preview Flashcards

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