Amoxicillin Mechanism — MFDS Part 1 MCQ
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Correct answer: D — Inhibition of bacterial cell wall synthesis
Explanation lettering: D = shown as A · A = shown as D
A is correct. Amoxicillin is an aminopenicillin and beta-lactam antibiotic. It binds to penicillin-binding proteins involved in bacterial peptidoglycan synthesis, impairing cell-wall cross-linking. The weakened wall ultimately undergoes lysis, particularly in actively dividing susceptible bacteria. Inhibition of the 30S ribosomal subunit is associated with agents such as tetracyclines and aminoglycosides. DNA gyrase is inhibited by fluoroquinolones, while bacterial folate synthesis is inhibited by sulfonamides and trimethoprim at different stages of the pathway. Direct disruption of the bacterial cell membrane is characteristic of agents such as polymyxins rather than amoxicillin.
Reference: Brown & Burk UK Ltd. Amoxicillin 500 mg Capsules, Summary of Product Characteristics, section 5.1 Pharmacodynamic properties: Mechanism of action. Updated 2026. https://www.medicines.org.uk/emc/product/10638/smpc