Question | Answer |
Is Staph Gram (+) or Gram (-)? | Gram positive |
What does Staph appear like on Gram stain? | "grape-like" clusters |
What is the lab media utilized for growing Staph? | agar with amino acids and B vitamens |
What is unique about the environment Staph can grow in? | It can grow in high concentrations of salt (>7.5%) |
Define the differences of S. aureus, S. Epidermidis, and S. saprophyticus as they would appear on agar (i.e. Colony color, mannitol fermentation) | S.aureus is yellow as opposed to S. epidermidis and S. Saprophyticus which are white.
S.aureus ferments mannitol whereas the others do not. |
What is the immunologic function of peptidoglycan? | Chemoattractant for PMN leukocytes
activator of the C3b alternative pathway for complement |
What is the function of teichoic acids? | Adherence |
How do gram positive bacteria cause shock? | Excessive inflammation causes epithelium damage
excessive activation of coagulaton pathway leads to blood clots
the combination of the two leads to multiple organ failure. |
What is the function of Protein A? | Anti-opsonin; binds FC portion of IgG |
What is fibronectin-binding protein? | It promotes binding to mucosal cells |
What is the function of the micro-capsule? | Anti-phagocytic due to high polysaccharide content |
What are the toxins and enzymes released by Staph? | Catalase, Coagulase, Hemolysins, Leukocidin, exfoliatin, enterotoxins |
what is the benefit of enterotoxins? | resist low pH of the stomach |
Why are superantigens so toxic? | Because they cause T cells to produce IL1, INF-y, TNF in toxic amounts |
How does Staph enter the body? | Damaged skin or mucous membranes |
What epidermolytic toxins cause scalded skin syndrome? | A and B |
what is the treament for a minor skin infection with staph? | Tetracycline |
what is the treatment for abscesses of Staph? | incision/drainage, methicillin or nafcillin |
How does Staph become resistance to penicillin? | Breakage of the beta- lactam ring |
how does staph become resistant to methicillin? | altered penicillin binding proteins that don't allow transpeptidase to bind protein. |
What does S.Epidermidis cause? | Introduced devices (catheters, valves, etc) |
S.Sapropyticus causes what? | UTI in females |