Staphylococci Flashcards
What is the 10,000-foot view of the differences between Staph. and Strep.?
Staphylococcus tends to localize and Streptococcus tends to spread.
True or false: Staphylococci are faculatative anaerobes.
False. They are aerobic.
Catalase-positive organisms will ______________ when you add hydrogen peroxide.
bubble (catalase-negative organisms will not)
What does coagulase do?
It clots fibrin. If you add coagulase-positive bacteria to plasma and let it sit, then it will form a clot.
In addition to being coagulase-negative, how else can you identify S. epidermidis in the lab?
It is not hemolytic (no light bulb or alpha signs in that kitchen where the plumber’s working!).
What is clumping factor?
It is a protein found in S. aureus that binds to fibrinogen and causes immediate clumping. Importantly, it does not require incubation –like coagulase does.
This protein allows S. aureus to clump.
S. aureus has ____________ on its surface.
protein A, which binds Fc and prevents opsonization
A = aureus = Moses’ staff
Sketchy left out an important feature of S. aureus: __________________.
it has a capsule
The bacterial surface protein that is found only in Gram-positive organisms binds to what protein?
Fibronectin (the protein being techoic acid)
What toxins cause scalded-skin syndrome?
Exfoliatin A and B
Which layer of skin do exfoliatin A and B target?
The granulosum –targeting desmosomes
Preformed ____________ causes rapid-onset food poisoning from S. aureus.
enterotoxin
The higher the MIC, the higher the _____________.
rate of therapeutic failure
If a strain of MRSA is sensitive to clindamycin, what should you test?
If it has erythromycin-induced resistance to clindamycin –does it have a positive D-test?
In terms of the pharmacotherapy options, coagulase-negative Staphylococcus should be treated like _______.
MRSA (that is, most coagulase-negative Staphylococci are resistant to ampicillin and cephalosporins)
