Post-antibiotic effect (PAE) is clinically exploited to allow once-daily dosing. Aminoglycosides exhibit prolonged PAE against gram-negative bacilli because:

• A They remain bound to 30S ribosomal subunits for a prolonged period after extracellular drug is removed
• B They induce bacterial sporulation, preventing regrowth for several hours
• C They are concentration-dependent killers that achieve a prolonged suppression of regrowth even after free drug levels fall below MIC, due to persistent ribosomal binding damage ✓
• D They penetrate biofilms and maintain bactericidal activity within the biofilm matrix

Explanation

Aminoglycosides are concentration-dependent antibiotics with a well-documented PAE (2–8 hours against aerobic gram-negatives). After extracellular drug is removed, bacteria fail to resume normal growth because aminoglycoside remains bound to 30S ribosomes causing persistent translational disruption. This PAE, combined with concentration-dependent killing, supports once-daily (extended interval) dosing, which maximises peak:MIC ratio while allowing drug-free intervals that reduce renal proximal tubular accumulation and nephrotoxicity. Aminoglycosides do not induce bacterial sporulation, and biofilm penetration is actually limited.

Reference: KD Tripathi, Essentials of Medical Pharmacology, 8th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.