Antibiotic Mechanisms

Question 1

Beta lactam mechanism and resistance

Answer 1

Inhibit peptidoglycan synthesis in cell walls by binding and inactivating penicillin binding proteins

Beta lactamases (most common), decrease in OM permeability (gram neg), mutation of penicillin binding proteins (s pneumoniae), novel PBP (MRSA)

Question 2

Vancomycin mechanism of action and resistance

Answer 2

Inhibits cell wall synthesis by binding D Ala D Ala terminal of growing peptide chain, inhibiting further elongation and cross linking

Resistance often theough altered D ala D ala sequence, preventing drug binding

Question 3

Bacitracin mechanism of action

Answer 3

Inhibits peptidoglycan synthesis by interfering with phosphorylase activity; bactericidal