Parallel evolutionary pathways to antibiotic resistance selected by biocide exposure

Mark A Webber, Rebekah N Whitehead, Manuella Mount, Nicholas Loman, Mark J Pallen, Laura J V Piddock

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51 Citations (Scopus)
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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.

Original languageEnglish
Pages (from-to)2241-2248
JournalJournal of Antimicrobial Chemotherapy
Issue number8
Early online date7 May 2015
Publication statusPublished - Aug 2015

Bibliographical note

© The Author 2015. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy.


  • disinfectant
  • MDR
  • efflux


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