The minimum biofilm eradication concentration (MBEC) of an antibiotic is typically how many folds higher than the planktonic MBC?

• A 2–4 times
• B Same as MBC — biofilm does not affect antibiotic activity
• C 0.5 times (biofilm bacteria are more susceptible)
• D 10–1000 times or more ✓

Explanation

Bacteria within biofilms exhibit dramatically increased tolerance to antibiotics — the minimum biofilm eradication concentration (MBEC) is typically 10 to 1000 times (or more) higher than the planktonic MBC, due to multiple mechanisms: slowed growth rate within biofilm reducing antibiotic target expression, extracellular matrix acting as a diffusion barrier, upregulation of efflux pumps, persister cell formation, and altered physiology. This extreme tolerance explains why device-associated infections (CLABSI, CAUTI, VAP, prosthetic joint infections) are notoriously difficult to eradicate with antibiotics alone and often require device removal.

Reference: Ananthanarayan & Paniker's Textbook of Microbiology, 11th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.