staph infections Flashcards
before answering this question draw the diagram for the gram positive bacteria
where is staph aureus usually found
what is the associated pigment
and what type of hemolysis is associated ?
normally found in the nose
yellow pigment
beta hemolytic
what is the virulence factor for staph aureus ?
protein A
binds Fc portion of the IgG antibody
has a lipid a core
antigen O
what are the toxin associated disease staph aureus ?
TSS toxic shock syndrome (TSST-1)
food poisoning ( staph enterotoxin )
scalded skin syndrome
what toxin is associated with scalded skin syndrome ?
exfoliative toxin
how would you be able to tell the difference between sepsis and toxic shock syndrome ?
resembles a sunburn may be associated with diarrhea and associated with desquamation
what is the classic scenario of staph food poisoning ?
food left in the sun for a long time
usually associated with potato or egg salads
what is the classic presentation of scalded skin syndrome ?
associated with newborns
positive nikolsky sign
what is the mechanism associated with scalded skin syndrome ?
staph aureus exfoliative toxin
only damages the keratinocytes in stratum granulosum
what is the causative organism in bullous impetigo vs impetigo ?
bullous - staph aureus
impetigo - group A Strep
what is the causative organism in subacute vs acute endocarditis ?
subacute - strep viridans needs prior valve abnormality
acute - staph aureus
what is the best prevention for staph bacteremia ?
proper sterile techniques
why are MRSA resistant to b lactams ?
they have altered penicillin binding proteins
what is the treatment for MRSA ?
vancomycin or daptomycin
where is staph epidermidis usually found ?
found in the normal skin flora
what are the 2 main linical implications of staph epidermidis ?
blood culture contamination
infections of prosthetics
what is the mechanism of infection that is assocated with staph epidermidis in prosthetics ?
allows for the formation of a biofilm
what is the most common cause of honeymoon cystitis ?
staph saprophyticus
which bacteria that cause UTI are associated with negative nitrites ?
enterococcus and staph saprophyticus
what antibiotic is used for the mtreatment of UTI ?
fluroquinolones
nitfurantoin
what is the classic cause of osteomyelitis in children ?
staph aureus
what is the classic cause of osteomyeloitis in sickle cell anemia patients ?
salmonella
what is the classic cause of osteomyelitis in TB patients ?
potts disese
what layers of the skin are affected by cellulitis ?
infection of the deep dermis and subcutaneous fat
what gene is responsible for the MRSA resistant factor ?
mecA gene
what is the virulence factor associated with community acquired MRSA ?
PVL
how would you differentiate between staph aureus and staph apidermidis in lab testing ?
s aures ferments mannitol whilst epidermidis doesnt
what type of immune response is associated with the TSST toxibnn ?
binds to MHC II and T cell receptor resulting in polycloonl t cell activation
what colour msputum is associated nwith pneumococcal pneumonia ?
rusty sputum
