Which factor makes bacteria most resistant to antimicrobials and host defenses?

Correct answer: B. Biofilm formation

• A. Free-floating bacteria are comparatively easy to kill.
• B. Correct. Within a biofilm, an extracellular matrix and altered metabolism dramatically increase resistance to antibiotics, disinfectants, and immune clearance.
• C. Cell-wall type affects staining/antibiotic class choice but is not the principal driver of multi-modal resistance described here.
• D. Aerobic metabolism alone does not confer broad resistance.