USMLE Micro

Question 1

What bacteria has Protein A and what does it do?

Answer 1

S. Aureus,

it prevents complement by binding to Fc region of Ig and prevent opsonization and phagocytosis

Question 2

What is IgA protease and what bacteria contain this enzyme?

Answer 2

It cleaves IgA. It is secreted by S. Pneumoniae, H. influenza type B, Neisseria in order to colonize respiratory mucosa.

(SHiN)

Question 3

Name 5 bacterial toxin encoded in lysogenic phase?

Answer 3

ShigA-like toxin

Botulimum toxin

Cholera Toxin

Diphtheria Toxin

Erythrogenic Toxin

ABCDE

Question 4

Name the 3 important Gram + rods

Answer 4

Clostridium

Listeria

Bacillus

Question 5

Novobiocin Test

What Staph is sensitive and what is resistant?

Answer 5

Saprophyticus is Resistant

S. Epidermidis is sensitive

No StRES

Question 6

Optochin Test

What does it test for ?

Answer 6

OVRPS.

Test for differentiation in Alpha hemotylic strep

Question 7

Bacitracin

What does it test for?

Answer 7

Beta hemolytic Group A and Group B Strep

B-BRAS