A 50-year-old man with active duodenal ulcer tests positive for Helicobacter pylori. Clarithromycin-based triple therapy (PPI, clarithromycin, amoxicillin) is prescribed. What is the primary mechanism of amoxicillin in H. pylori eradication?
- A Inhibition of bacterial cell wall synthesis by binding to penicillin-binding proteins ✓
- B Inhibition of bacterial protein synthesis by binding to the 50S ribosomal subunit
- C Disruption of bacterial DNA gyrase and topoisomerase IV
- D Inhibition of bacterial folate synthesis by competitive DHFR inhibition
Correct answer: A. Inhibition of bacterial cell wall synthesis by binding to penicillin-binding proteins
Explanation
Amoxicillin is a beta-lactam antibiotic that inhibits bacterial cell wall synthesis by binding to penicillin-binding proteins (PBPs), preventing peptidoglycan cross-linking. This bactericidal mechanism is effective against H. pylori. Clarithromycin (50S ribosome) and metronidazole (DNA disruption) have different mechanisms. Amoxicillin resistance in H. pylori is uncommon.
Reference: Katzung Basic and Clinical Pharmacology, 15th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.