ID Resistance Mechs

Question 1

Vancomycin

Answer 1

Mutation of peptidoglycan cell wall precursor (D-Ala-D-Lactate)

Question 2

Synercid

Answer 2

Quinupristin: adenine methylation of A2058

Question 3

Linezolid

Answer 3

Target site modification at 2576

Question 4

Aminoglycosides

Answer 4

1. Metabolism (acetylation, adenylation, phosphorylation)
2. Altered Ribosomes
3. Altered aminoglycoside uptake

Question 5

Macrolides

Answer 5

“Macrolides are LAME”
1. Lactone Ester hydrolase
2. Adenine base (A2058) is methylated
3. Mutation of adenine to guanine on A2058
4. Efflux pump

5. Intrinsic Resistance: Pseudomonas and Enterobacter don’t allow drug in

Question 6

Chloramphenicol

Answer 6

1. Dec Membrane permeability
2. Mut of 50S subunit
3. Chloramphenicol acetyltransferase (inactive metabolite formation)

Question 7

Quinolones

Answer 7

1. Dec cellular permeability
2. Efflux Pumps
3. mutations of target enzymes (A-subunit of DNA gyrase)

Question 8

B-Lactams

Answer 8

B-Lactamase