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Chlorhexidine Mechanism — MFDS Part 1 MCQ

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ModeratePharmacologyChlorhexidine MechanismMFDS Part 1

Which sequence most accurately describes the primary antibacterial action of a chlorhexidine digluconate mouthwash?

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Correct answer: A — Electrostatic binding to anionic bacterial surfaces, followed by disruption of membrane permeability

Chlorhexidine is a cationic bisbiguanide. Its positive charge promotes interaction with negatively charged bacterial surfaces and acidic membrane phospholipids. This alters membrane permeability, causing leakage of intracellular constituents; at higher concentrations, precipitation of cellular contents contributes to bactericidal activity. Therefore, A is correct. DNA gyrase inhibition is characteristic of fluoroquinolones, whereas inhibition of dihydropteroate synthase is the mechanism of sulfonamides. Penicillin-binding proteins and peptidoglycan cross-linking are targeted by beta-lactams. Binding to the 30S ribosomal subunit with mRNA misreading is associated principally with aminoglycosides.

Reference: Electronic Medicines Compendium. ChloraPrep with Tint, Summary of Product Characteristics, section 5.1 Pharmacodynamic properties: Mechanism of action. Revised 5 January 2026. https://www.medicines.org.uk/emc/product/496/smpc