Adaptive microbial response to low-level benzalkonium chloride exposure

Area of Science:

• Microbiology
• Antimicrobial Resistance
• Public Health

Background:

• Benzalkonium chloride (BAC) is a common biocide in disinfectants.
• Its widespread use raises concerns about bacterial adaptation and resistance.
• Understanding bacterial adaptation to BAC is crucial for infection control.

Purpose of the Study:

• To review the potential for bacteria to adapt to low-level benzalkonium chloride exposure.
• To assess the implications of BAC adaptation on disinfectant efficacy.
• To provide recommendations on the use of BAC in various settings.

Main Methods:

• Systematic review of studies evaluating bacterial adaptation to benzalkonium chloride.
• Analysis of changes in minimum inhibitory concentrations (MICs) across various bacterial species.
• Investigation of cross-resistance patterns and genetic mechanisms (e.g., efflux pumps).

Main Results:

• Most of the 57 evaluated bacterial species showed up to a four-fold increase in MIC.
• Significant, stable adaptation (up to 500-fold increase in MIC) observed in Pantoea spp., Enterobacter spp., Staphylococcus saprophyticus, and Escherichia coli.
• Cross-resistance to antibiotics and other biocides was noted, alongside upregulation of transporter and efflux pump genes in adapted bacteria.

Conclusions:

• Adapted bacterial isolates may survive recommended concentrations of BAC disinfectants.
• The use of BAC in healthcare, consumer products, and households requires critical assessment and restriction.
• Prioritize biocidal agents with lower selection pressure when efficacy and compatibility are comparable.