Staphylococci Flashcards Preview

MS2 - Infectious Disease > Staphylococci > Flashcards

Flashcards in Staphylococci Deck (22)
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1
Q

What is the 10,000-foot view of the differences between Staph. and Strep.?

A

Staphylococcus tends to localize and Streptococcus tends to spread.

2
Q

True or false: Staphylococci are faculatative anaerobes.

A

False. They are aerobic.

3
Q

Catalase-positive organisms will ______________ when you add hydrogen peroxide.

A

bubble (catalase-negative organisms will not)

4
Q

What does coagulase do?

A

It clots fibrin. If you add coagulase-positive bacteria to plasma and let it sit, then it will form a clot.

5
Q

In addition to being coagulase-negative, how else can you identify S. epidermidis in the lab?

A

It is not hemolytic (no light bulb or alpha signs in that kitchen where the plumber’s working!).

6
Q

What is clumping factor?

A

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.

7
Q

S. aureus has ____________ on its surface.

A

protein A, which binds Fc and prevents opsonization

A = aureus = Moses’ staff

8
Q

Sketchy left out an important feature of S. aureus: __________________.

A

it has a capsule

9
Q

The bacterial surface protein that is found only in Gram-positive organisms binds to what protein?

A

Fibronectin (the protein being techoic acid)

10
Q

What toxins cause scalded-skin syndrome?

A

Exfoliatin A and B

11
Q

Which layer of skin do exfoliatin A and B target?

A

The granulosum –targeting desmosomes

12
Q

Preformed ____________ causes rapid-onset food poisoning from S. aureus.

A

enterotoxin

13
Q

The higher the MIC, the higher the _____________.

A

rate of therapeutic failure

14
Q

If a strain of MRSA is sensitive to clindamycin, what should you test?

A

If it has erythromycin-induced resistance to clindamycin –does it have a positive D-test?

15
Q

In terms of the pharmacotherapy options, coagulase-negative Staphylococcus should be treated like _______.

A

MRSA (that is, most coagulase-negative Staphylococci are resistant to ampicillin and cephalosporins)

16
Q

CGD has what pattern of inheritance?

A

XLR

CGD = Can’t Get Dames

17
Q

If you have antibody to TSST, then __________.

A

you can still develop local bullous impetigo but not systemic infection

18
Q

Which two genes allow S. aureus to be resistant to beta-lactams?

A

mecA and PBP2A

19
Q

Cold abscesses are a sign of ____________.

A

Job syndrome

20
Q

Milder cytokine responses to TSST cause _______________.

A

scarlet fever

21
Q

Mild S. aureus skin infections should be treated with _____________.

A

cephalexin

22
Q

Severe S. aureus skin infections should be treated with _____________.

A

nafcillin and cephalexin or vancomycin or clindamycin