Pharmacology · Antimicrobials (Cell Wall Inhibitors, Protein Synthesis Inhibitors, Fluoroquinolones)

Ceftazidime-avibactam differs from ceftazidime alone in that avibactam inhibits which class of beta-lactamases that clavulanic acid cannot inhibit?

  • A Class B metallo-beta-lactamases (NDM, VIM, IMP)
  • B Extended-spectrum beta-lactamases (ESBLs) only
  • C Class A (KPC), Class C (AmpC), and Class D (OXA) beta-lactamases ✓
  • D OXA-48 carbapenemases only
Correct answer: C. Class A (KPC), Class C (AmpC), and Class D (OXA) beta-lactamases

Explanation

Avibactam is a novel non-beta-lactam beta-lactamase inhibitor (diazabicyclooctane class) that inhibits Class A (including KPC-type carbapenemases), Class C (AmpC), and Class D (OXA-48-type) serine beta-lactamases by forming a covalent but reversible acyl-enzyme complex. Clavulanic acid is a suicide inhibitor effective primarily against Class A beta-lactamases but not AmpC or OXA-48. Critically, avibactam does NOT inhibit Class B metallo-beta-lactamases (NDM, VIM, IMP), which require zinc ions; ceftazidime-avibactam is therefore ineffective against NDM-producing organisms.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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