The mechanism by which beta-lactamase inhibitors (e.g., clavulanate) restore the activity of amoxicillin against resistant organisms is:
- A They competitively inhibit PBP2a in MRSA
- B They increase the outer membrane permeability of gram-negative bacteria
- C They irreversibly bind to and inactivate beta-lactamase enzymes ✓
- D They prevent efflux pump-mediated antibiotic extrusion
Correct answer: C. They irreversibly bind to and inactivate beta-lactamase enzymes
Explanation
Clavulanate contains a beta-lactam ring that acts as a 'suicide substrate' or 'mechanism-based inhibitor' — it irreversibly acylates beta-lactamase enzymes, permanently inactivating them and allowing the co-administered beta-lactam (amoxicillin) to reach its PBP targets intact. This strategy does not overcome MRSA's PBP2a alteration, efflux pumps, or porin defects.
Reference: KD Tripathi, Essentials of Medical Pharmacology, 8th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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