title: Reduced susceptibilities to biocides and resistance to antibiotics in food-associated bacteria following exposure to quaternary ammonium compounds.
abstract: OBJECTIVE
  Our aim was to assess the effects of step-wise exposure to didecyl dimethyl ammonium chloride (DDAC) on the antimicrobial (antibiotics and biocides) susceptibilities of food-associated bacterial strains.
  
  
  RESULTS
  Adaptive responses of bacterial strains were investigated by exposing the strains daily to increasing subinhibitory concentrations of DDAC for 7 days. Following adaptation to DDAC, a threefold increase in the minimum inhibitory concentration (MIC) values for this biocide was observed in 48% of the Escherichia coli and Listeria monocytogenes strains, and 3% of the Salmonella strains. Reduced susceptibility to other biocides was found with the most important increase in MIC for benzalkonium chloride (BC) and a commercial biocide formulation (Galox Horizon) containing DDAC and glutaraldehyde, for all species except Salmonella. Increase in antibiotic MIC values was more pronounced in E. coli in terms of antibiotic numbers and of magnitude (from 4- to 32-fold increase) and, to a lesser extent, in Salmonella strains. Most of these strains had acquired resistance to ampicillin, cefotaxime, ceftazidime, chloramphenicol and ciprofloxacin.
  
  
  CONCLUSIONS
  The effects of exposure to DDAC on biocides and antibiotics susceptibilities depend upon the bacteria species.
  
  
  CONCLUSIONS
  Extensive use of DDAC at subinhibitory concentrations may lead to the development of antibiotic-resistant bacteria and may represent a public health issue.
authors.affiliation: Antibiotics, Biocides, Residues and Resistance Unit, Fougères Laboratory, ANSES, Fougères, France. christophe.soumet@anses.fr.
authors.forename: C
authors.initials: C
authors.lastname: Soumet
authors.affiliation: Biology Department, University of Rennes 1, IUT Saint-Brieuc, Saint-Brieuc, France.
authors.forename: D
authors.initials: D
authors.lastname: Méheust
authors.affiliation: Biology Department, University of Rennes 1, IUT Saint-Brieuc, Saint-Brieuc, France.
authors.forename: C
authors.initials: C
authors.lastname: Pissavin
authors.affiliation: Antibiotics, Biocides, Residues and Resistance Unit, Fougères Laboratory, ANSES, Fougères, France.
authors.forename: P
authors.initials: P
authors.lastname: Le Grandois
authors.affiliation: Department of Fresh and Processed Meat, IFIP, Maisons-Alfort, Le Rheu, France.
authors.forename: B
authors.initials: B
authors.lastname: Frémaux
authors.affiliation: Department of Fresh and Processed Meat, IFIP, Maisons-Alfort, Le Rheu, France.
authors.forename: C
authors.initials: C
authors.lastname: Feurer
authors.affiliation: Department of Fresh and Processed Meat, IFIP, Maisons-Alfort, Le Rheu, France.
authors.forename: A
authors.initials: A
authors.lastname: Le Roux
authors.affiliation: Hygiene and Quality of Poultry and Pork Products Unit, Ploufragan-Plouzané Laboratory, ANSES, Ploufragan, France.
authors.forename: M
authors.initials: M
authors.lastname: Denis
authors.affiliation: Antibiotics, Biocides, Residues and Resistance Unit, Fougères Laboratory, ANSES, Fougères, France.
authors.forename: P
authors.initials: P
authors.lastname: Maris
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001548:Benzalkonium Compounds / Q000494:pharmacology; D004202:Disinfectants / Q000494:pharmacology*; D024881:Drug Resistance, Bacterial; D004926:Escherichia coli / Q000187:drug effects; D005516:Food Microbiology; D008089:Listeria monocytogenes / Q000187:drug effects; D000644:Quaternary Ammonium Compounds / Q000494:pharmacology*; D012475:Salmonella / Q000187:drug effects
chemical_list: D000900:Anti-Bacterial Agents; D001548:Benzalkonium Compounds; D004202:Disinfectants; D000644:Quaternary Ammonium Compounds; C027118:didecyldimethylammonium
keywords: 
  QAC
  ; adaptation; antibiotics; decreased susceptibility; disinfectants; resistance