At high concentrations, chlorhexidine is primarily:

At high concentrations, chlorhexidine is primarily:

• A. Bacteriostatic at high concentrations
• B. Sporicidal at high concentrations
• C. Bactericidal at low concentrations
• D. Bactericidal at high concentrations

Answer: (D)

Concentration-dependent action of chlorhexidine on bacteria is being tested. At lower concentrations it binds to the cell envelope and causes leakage in a reversible way, which slows growth without instantly killing the cell (bacteriostatic). When the concentration is high enough, chlorhexidine disrupts the cell membrane more aggressively and precipitates cytoplasmic contents, leading to rapid cell death (bactericidal). It is not sporicidal, since bacterial spores are highly resistant and chlorhexidine does not reliably kill them. Therefore, bactericidal at high concentrations best describes chlorhexidine’s effect.

Concentration-dependent action of chlorhexidine on bacteria is being tested. At lower concentrations it binds to the cell envelope and causes leakage in a reversible way, which slows growth without instantly killing the cell (bacteriostatic). When the concentration is high enough, chlorhexidine disrupts the cell membrane more aggressively and precipitates cytoplasmic contents, leading to rapid cell death (bactericidal). It is not sporicidal, since bacterial spores are highly resistant and chlorhexidine does not reliably kill them. Therefore, bactericidal at high concentrations best describes chlorhexidine’s effect.