Reduction in chlorhexidine efficacy against multi-drug-resistant Acinetobacter baumannii international clone II

Area of Science:

• Microbiology
• Infectious Diseases
• Antimicrobial Resistance

Background:

• Nosocomial infections caused by Acinetobacter baumannii international clone II (IC II) pose significant clinical challenges.
• IC II strains are associated with severe patient outcomes.

Purpose of the Study:

• To comparatively assess the bactericidal effectiveness of chlorhexidine gluconate (CHX) and benzethonium chloride (BZT) against IC II and non-IC II Acinetobacter baumannii isolates.
• To determine the susceptibility profiles of these isolates to CHX and BZT.

Main Methods:

• Minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) of CHX and BZT were determined for 137 IC II, 99 non-IC II, and 69 non-baumannii isolates.
• Time-kill curves were generated to evaluate the bactericidal kinetics of the disinfectants.
• The influence of bovine serum albumin (BSA) on disinfectant efficacy was investigated.

Main Results:

• CHX and BZT exhibited MIC90 values of 100mg/L and 175mg/L for IC II isolates, respectively.
• Both disinfectants rapidly reduced bacterial populations by 5 log10 within 30 seconds at 1000mg/L, regardless of IC II status.
• CHX maintained efficacy in the presence of BSA, while BZT's efficacy decreased with BSA addition.

Conclusions:

• CHX and BZT are effective against Acinetobacter species, including IC II, at a concentration of 1000mg/L with 30-second exposure.
• Careful consideration of disinfectant concentrations is crucial for ensuring adequate efficacy in clinical and healthcare settings.
• The presence of organic matter (BSA) impacts BZT efficacy more than CHX.