title: Resistance to phenicol compounds following adaptation to quaternary ammonium compounds in Escherichia coli.
abstract: Bacterial adaptation to quaternary ammonium compounds (QACs) is mainly documented for benzalkonium chloride (BC) and few data are available for other QACs. The aim of this study was to assess the effects of repeated exposure to different quaternary ammonium compounds (QACs) on the susceptibility and/or resistance of bacteria to other QACs and antibiotics. Escherichia coli strains (n=10) were adapted by daily exposure to increasingly sub-inhibitory concentrations of a QAC for 7 days. Three QACs were studied. Following adaptation, we found similar levels of reduction in susceptibility to QACs with a mean 3-fold increase in the minimum inhibitory concentration (MIC) compared to initial MIC values, whatever the QAC used during adaptation. No significant differences in antibiotic susceptibility were observed between the tested QACs. Antibiotic susceptibility was reduced from 3.5- to 7.5-fold for phenicol compounds, β lactams, and quinolones. Increased MIC was associated with a shift in phenotype from susceptible to resistant for phenicol compounds (florfenicol and chloramphenicol) in 90% of E. coli strains. Regardless of the QAC used for adaptation, exposure to gradually increasing concentrations of this type of disinfectant results in reduced susceptibility to QACs and antibiotics as well as cross-resistance to phenicol compounds in E. coli strains. Extensive use of QACs at sub-inhibitory concentrations may lead to the emergence of antibiotic-resistant bacteria and may represent a public health risk.
authors.affiliation: Agence nationale de sécuritaire sanitaire de l'aliment, de l'environnement et du travail (Anses), Laboratoire de Fougères, Unité Produits d'Hygiène Anti-Microbiens, BP 90203, 35302 Fougères Cedex, France. Christophe.SOUMET@anses.fr
authors.forename: C
authors.initials: C
authors.lastname: Soumet
authors.forename: E
authors.initials: E
authors.lastname: Fourreau
authors.forename: P
authors.initials: P
authors.lastname: Legrandois
authors.forename: P
authors.initials: P
authors.lastname: Maris
mesh_terms: D000222:Adaptation, Physiological / Q000187:drug effects; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001548:Benzalkonium Compounds / Q000494:pharmacology; D002701:Chloramphenicol / Q000494:pharmacology*; D004202:Disinfectants / Q000494:pharmacology*; D024881:Drug Resistance, Bacterial; D004926:Escherichia coli / Q000187:drug effects* / Q000502:physiology; D005516:Food Microbiology; D008826:Microbial Sensitivity Tests; D000644:Quaternary Ammonium Compounds / Q000494:pharmacology*
chemical_list: D000900:Anti-Bacterial Agents; D001548:Benzalkonium Compounds; D004202:Disinfectants; D000644:Quaternary Ammonium Compounds; D002701:Chloramphenicol