Micro

Question 1

A teenager leaves her tampon in too long and presents with fever, vomiting, and shock. What notable findings will the labs reveal?

Pathogen?

TTS in Staph vs Strep?

Answer 1

High AST, ALT, and bilirubin

Toxic shock syndrome caused by TSST-1, a superantigen that binds MHC II and T-cell receptors, resulting in polyclonal T-cell activation

S aureus TSS = fever, vomiting, rash, desquamation, shock, and end-organ failure;

S pyogenes TSS = painful skin infection

Question 2

You are terrified of S aureus food poisoning and overcook your food. Does this help?

Answer 2

No; the enterotoxin is heat stable and not destroyed by cooking

Question 3

A patient is found to have S aureus. Describe the clinical significance of the organism’s being coagulase positive.

Answer 3

It allows the organism to form a fibrin clot around itself, permitting abscess formation

Question 4

A patient has MRSA. What protein is altered in MRSA that grants resistance to β-lactams? Name two drugs that are useless against MRSA.

A scientist working on MRSA knocks out the bacteria’s penicillinases but finds that the bug is still resistant to several penicillins. Why?

Answer 4

Penicillin-binding protein; methicillin and nafcillin

MRSA alters its penicillin-binding proteins to resist killing by penicillinase-stable penicillins (eg, methicillin, oxacillin, nafcillin)