staphylococcus aureus Flashcards
Staph aureus is coagulase? and catalase?
catalase and coagulase +
how do colonies of stap aureus look like?
yellow colonies in mannitol salt agar
Staph aureus can tolerate high concentration of what substance?
salt
where does stap aureus ferment?
in mannitol
Staph aureus is resistant to what?
1) penicillin
2) methicillin
3) vancomycin
why is stap aureus resistant to penicillin?
it has penicillinase
what is used for treatment when there is resistance to penicillin?
oxacillin
why is staph aureus resistant to methicillin (MRSA)?
it modifies PBP which has low affinity for beta lactam drugs
how do you treat methicillin resistant staph aureus?
vancomycin
how does staph aureus become resistant to vancomycin (VRSA)?
converts D-Ala-D-Ala to D-Ala-D-Lac
what is used to treat VRSA?
quinupristin and dalfopristin
what illnesses are related to toxins from staph aureus? (3)
staph scalded skin syndrome = exfoliate toxin
food poisoning = enterotoxin
Toxic Shock Syndrome = TSST-1
what enzymes does staph aureus produce?
catalase
coagulase
protein A
cytolytic toxins
enterotoxins
exfoliative
toxic shock syndrome toxin-1 (TSST-1)
what is toxic shock syndrome toxin-1?
what is its onset?
what symptoms are seen?
it is a superantigen where there is non-specific activation of T lymphocytes and consequent release of a large number of cytokines
it has an acute onset
fever, hypotension, multiple system organ failure
what do the exfoliative enzymes of staph aureus cause?
what is seen with this?
what age must people have for this to happen?
what is a complication that can happen with the disease caused by exfoliative enzymes of staph aureus?
Staph scalded skin syndrome (SSSS),
A-B toxin targets epithelial cells and breaks it (targets tight junctions and desmosomes)
on children 6 or below
bullous impetigo (localized SSSS), will have impetigo but with fever