title: Resistance to quaternary ammonium compounds in food-related bacteria.
abstract: Microbial resistance to antimicrobial agents continues to be a major problem. The frequent use and misuse of disinfectants based on quaternary ammonium compounds (QACs) in food-processing industries have imposed a selective pressure and may contribute to the emergence of disinfectant-resistant microorganisms. A total number of 1,325 Gram-negative isolates (Escherichia coli, other coliforms Vibrio spp., and Aeromonas spp.) and 500 Enterococcus spp. from food and food-processing industries and fish farming were screened for natural resistance to the QAC-based disinfectant benzalkonium chloride (BC). Of the 1,825 isolates, 16 strains, mainly from meat retail shops, showed low-level resistance to BC. None of the Enterococcus spp. from broiler, cattle, and pigs, the antibiotic-resistant E. coli from pig intestine and fish pathogens Vibrio spp. and Aeromonas spp. from the Norwegian fish farming industry were resistant to BC. The BC-resistant strains were examined for susceptibility to 15 different antibiotics, disinfectants, and dyes. No systematic cross-resistance between BC and any of the other antimicrobial agents tested was detected. Stable enhanced resistance in Enterobacter cloacae isolates was demonstrated by step-wise adaptation in increasing concentrations of BC. In conclusion, BC resistance among food-associated Gram-negative bacteria and Enterococcus spp. is not frequent, but resistance may develop to user concentrations after exposure to sublethal concentrations of BC.
authors.affiliation: MATFORSK, Norwegian Food Research Institute, N-1430 As, Norway.
authors.forename: Maan Singh
authors.initials: MS
authors.lastname: Sidhu
authors.forename: Henning
authors.initials: H
authors.lastname: Sørum
authors.forename: Askild
authors.initials: A
authors.lastname: Holck
mesh_terms: D000222:Adaptation, Physiological; D000818:Animals; D000891:Anti-Infective Agents, Local / Q000494:pharmacology; D001419:Bacteria / Q000187:drug effects*; D001548:Benzalkonium Compounds / Q000494:pharmacology; D002417:Cattle; D003470:Culture Media; D024881:Drug Resistance, Bacterial; D016983:Enterococcus / Q000187:drug effects; D005399:Fishes; D005516:Food Microbiology; D006090:Gram-Negative Bacteria / Q000187:drug effects; D008826:Microbial Sensitivity Tests; D000644:Quaternary Ammonium Compounds / Q000494:pharmacology*; D013552:Swine
chemical_list: D000891:Anti-Infective Agents, Local; D001548:Benzalkonium Compounds; D003470:Culture Media; D000644:Quaternary Ammonium Compounds