Question

Mechanism of antibacterial action of polymyxins relies on the

• A. inhibition of 30S ribosomal subunit
• B. disruption of peptidoglycan synthesis
• C. inhibition of DNA replication of bacteria
• D. disruption of membrane architecture of bacteria

Hint:

Remember: Polymyxins = membrane disruptors (esp. Gram-negative).

Answer 1

The Correct Option is D

Step 1: Recall polymyxins.
Polymyxins are cationic polypeptide antibiotics that interact with lipopolysaccharides (LPS) of Gram-negative bacterial outer membranes.
Step 2: Mechanism.
- They bind to phospholipids.
- Disrupt membrane permeability.
- Cause leakage of cellular contents and bacterial death.
Step 3: Rule out other mechanisms.
- (A) Inhibition of 30S ribosome: Done by aminoglycosides, tetracyclines.
- (B) Inhibition of peptidoglycan synthesis: Done by β-lactams, vancomycin.
- (C) Inhibition of DNA replication: Done by quinolones.
Final Answer: \[ \boxed{\text{Polymyxins disrupt bacterial membrane architecture.}} \]