Microbiology: Staphylococcus Flashcards
what properties of the skin act as defence against infection
dryness(desiccation of microorganisms), sebum(inhibit bacterial growth), competitive bacterial flora(resident and transient)
what organisms are involved in the competitive bacterial flora
staphylococcus epidermidis, corynebacterium sp.(diphtheroids), propionibacterium sp.
what tests are used to diagnose the type of bacteria causing infection
swab of lesion if surface broken, pus or tissue if deeper lesion, +/- blood cultures if appropriate
what is the difference between staph aureus and coagulase negative staph on blood agar plate
staph aureus = golden
coagulase negative staph = white/colourless
describe the appearance of staph aureus
gram positive cocci in clusters
describe the growth of staph aureus
aerobic and facultatively anaerobic, ie grow best in air but can grow without
what are the 2 important types of staphylococcus
staph aureus and coagulase negative staph(eg epidermidis)
what types of infections does staph aureus cause
wound, skin, bone and joint infections
what distinguishes staph aureus from any other staphylococcus species
produces coagulase enzyme
what is the antibiotic of choice for staph aureus
flucloxacillin
what is a common resistant strain of staph aureus
MRSA(Methicillin Resistant Staph Aureus)
what bacterial skin infections can staph aureus
boils + carbuncles, minor skin sepsis, cellulitis, infected eczema, impetigo, wound infection
what are the options for MRSA treatment
doxycycline, co-trimoxazole, clindamycin, vancomycin
NOT flucloxacillin
describe where coagulase negative staphs are usually seen
as skin commensals, not usually pathogenic
when may coagulase negative staphs cause infection
in association with implanted foreign material, such as artificial joints, valves, IV catheters etc.
