Staphylococci Flashcards Preview

Medical Microbiology > Staphylococci > Flashcards

Flashcards in Staphylococci Deck (19):
1

S. aureus appearance

Gram positive cocci, forms clusters, coagulase positive

2

Virulence factors

Biofilm, surface proteins that bind to collagen, fibronectin, ferritin, and secreted proteins.

3

Main virulence factor for Staph aureus? How does it work?

Protein A, binds to the Fc terminal of IgG inhibiting complement fixation and phagocytosis.

4

Main type of S. aureus pathology?

Abscess

5

How else (besides protein A) does S. aureus evade opsonization?

Polysaccharide capsule

6

What are more virulent, coagulase positive or coagulase negative staphylococci?

Coagulase positive (S. aureus) is more virulent than coagulase negative (S. epidermidis).

7

Toxin mediated staph pathogenesis

Toxic shock syndrome by TSST1, scalded skin syndrome, rapid onset food poisoning (preformed toxin).

8

Which toxic shock syndrome is more severe, group A strep or staph aureus?

Strep

9

How does Staphylococcus aureus adherence promote survival?

A polysaccharide web is created that is impermeable to antibodies and too big to phagocytose. Forms a slime layer that promotes seeding

10

Why do we have to treat a patient with a staph positive blood smear for 4 weeks, when we don't really have to worry about a strep positive blood smear?

Because staph is really sticky and can (and will) land anywhere. If its in the blood, its already seeded into a colony.

11

Staph aureus skin infections

Abscess, impetigo, cellulitis, chalazion

12

Staph vs strep viridians endocarditis

Staph affects normal valves, and strep viridians affects damaged valves

13

Staph effects on bone and muscle

Can cause abscesses, osteomyelitis, and septic arthritis

14

Can staph cause pneumonia?

Yes, for people with ventilators. Staph is a common cause of hospital based infections.

15

T/F Staphylococcus aureus is a frequent cause of hospital based infections.

True

16

Staph aureus food poisoning

Caused by preformed endotoxin. Generally when a dairy food has been left unrefrigerated.

17

MRSA

Limited therapeutic options, community and hospital (more severe) strains exist. Treat with vancomycin.

18

Features of staph epidermidis

Coagulase negative, common normal inhabitant of skin, almost never causes disease except for those with medical devices.

19

Staphylococcus saprophyticus can cause...

Urinary tract infections, may be able to bind unique receptors in mucosa.