Parallel evolutionary pathways to antibiotic resistance selected by biocide exposure

J Antimicrob Chemother. 2015 Aug;70(8):2241-8. doi: 10.1093/jac/dkv109. Epub 2015 May 7.

Abstract

Objectives: Biocides are widely used to prevent infection. We aimed to determine whether exposure of Salmonella to various biocides could act as a driver of antibiotic resistance.

Methods: Salmonella enterica serovar Typhimurium was exposed to four biocides with differing modes of action. Antibiotic-resistant mutants were selected during exposure to all biocides and characterized phenotypically and genotypically to identify mechanisms of resistance.

Results: All biocides tested selected MDR mutants with decreased antibiotic susceptibility; these occurred randomly throughout the experiments. Mutations that resulted in de-repression of the multidrug efflux pump AcrAB-TolC were seen in MDR mutants. A novel mutation in rpoA was also selected and contributed to the MDR phenotype. Other mutants were highly resistant to both quinolone antibiotics and the biocide triclosan.

Conclusions: This study shows that exposure of bacteria to biocides can select for antibiotic-resistant mutants and this is mediated by clinically relevant mechanisms of resistance prevalent in human pathogens.

Keywords: MDR; disinfectant; efflux.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Disinfectants / pharmacology*
  • Drug Resistance, Bacterial*
  • Evolution, Molecular*
  • Genotype
  • Humans
  • Microbial Sensitivity Tests
  • Mutation
  • Phenotype
  • Salmonella typhimurium / drug effects*
  • Salmonella typhimurium / genetics*
  • Selection, Genetic*

Substances

  • Disinfectants