Question

In what population(s) do(es) Staphylococcus aureus cause infections? What types of infections are associated with S. aureus? How does Protein A contribute to the virulence of S. aureus? What toxin causes toxic shock syndrome? What type of toxin is associated with scalded skin syndrome? What toxins are involved in staphylococcal food poisoning? In what clinical condition would coagulase-negative staphylococci be significant? Which coagulase-negative staphylococci are considered more significant, and might need to be identified to the species level? What are the two types of coagulase produced by S. aureus, and how is each type detected in the clinical lab?

Answer 1

1. Staph are bacteria commonly colonized (bacteria are present but not causing infection) on the skin or in the nose of 20-30% of healthy population as but people with weakened immune system are at more risk of staph infections.

2. Staph cause a range of illness from minor skin infections like pimples, boils, impetigo,folliculitis, carbuncles, scalded skin syndrome to serious life threatening infections like toxic shock syndrome, sepsis, bacteremia, pneumonia, meningitis

3. Protein A is a surface protein seen in staph cellwall and is released during the growth of bacteria. Proteinbinds to the Fc region as well as the Fab domain of V_H3 clan IgG and IgM antibod, therby protecting the staph from opsonophagocytic killing

4. Toxic Shock Syndrome Toxin

5. Epidermolytic toxin A and B

6. Staphylococcal Enterotoxin B

7. immunecompromised patients and chronic disease patients are more prone to Coagulase negative staph

8. S. epidermidis is most prevelant coagulase negative staph

9. Bound coagulase (Clumping factor) and free coagulase two types produced by S. aureus

Bound coagulase can be detected by slide coagulase test

Free coagulase can be detected by Tube coagulase test