Resistance to quaternary ammonium compounds in food-related bacteria.
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.
Sidhu
Maan Singh
MS
MATFORSK, Norwegian Food Research Institute, N-1430 As, Norway.
Sørum
Henning
H
Holck
Askild
A
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
D000891:Anti-Infective Agents, Local; D001548:Benzalkonium Compounds; D003470:Culture Media; D000644:Quaternary Ammonium Compounds