Disinfectants facilitate the transformation of exogenous antibiotic resistance genes via multiple pathways

Area of Science:

• Microbiology
• Environmental Science
• Public Health

Background:

• Multidrug-resistant (MDR) bacteria and antibiotic resistance genes (ARGs) present a significant global health threat.
• Horizontal gene transfer, particularly natural transformation, is a key mechanism for ARG dissemination.
• The impact of disinfectants, widely used during the COVID-19 pandemic, on ARG transformation remains largely unexplored.

Purpose of the Study:

• To investigate the effect of common disinfectants on the natural transformation of plasmid-borne ARGs.
• To elucidate the underlying mechanisms by which disinfectants influence bacterial transformation.

Main Methods:

• Assessing the transformation efficiency of resistance plasmids in E. coli DH5α recipient bacteria exposed to disinfectants (benzalkonium bromide, benzalkonium chloride, PHMG) at environmentally relevant concentrations.
• Analyzing changes in bacterial membrane permeability, gene expression (membrane-related, secretion system-related), respiration, ATP production, and flagellum motility.

Main Results:

• Benzalkonium bromide, benzalkonium chloride, and PHMG significantly enhanced the transformation of plasmid-encoded ARGs.
• Disinfectants increased bacterial membrane permeability and promoted the expression of membrane-related genes.
• Disinfectants boosted bacterial respiration, ATP production, flagellum motility, and increased the expression of bacterial secretion system-related genes.

Conclusions:

• Environmentally relevant concentrations of certain disinfectants can promote the spread of antibiotic resistance genes via bacterial transformation.
• Disinfectants may contribute to ARG dissemination by altering bacterial physiology, including membrane permeability, respiration, and motility.
• The widespread use of disinfectants may pose an underestimated risk for the proliferation of antibiotic resistance.