Staph Aureus

Question 1

What type of cell wall does staph a. have?

Answer 1

peptidogylcan

Question 2

What is different about peoples immunity that are non carriers of staph a.?

Answer 2

Elevated Beta 3 defensin

Question 3

What are five virulence factors of SA?

Answer 3

Haemolysin- lyses neutrophils
catalase- converts H202 into 02 whilst in phagosome
CHPS- prevents chemotaxis
Clumping factor (A)- binds fibrinogen, no immune recognition
Protein A - Binds Ig Heavy chain, masks SA
Hyaluronidase and lipase for invasion

Question 4

How would you treat SA?

Answer 4

Antibiotics (penicillin), stablise and drain pus

Question 5

How does penicillin work?

Answer 5

Inhibits transpeptidase enzyme (enzyme involved in building peptiodglycan cell wall). Cell will lyse.

Question 6

How did SA become resistant and what is the methicillin resistant strain caused?

Answer 6

Beta lactamase enzyme, tried methicillin —> MRSA (altered transpeptidase structure)