Submitted to: National Antimicrobial Resistance Monitoring System Scientific Meeting
Publication Type: Abstract Only
Publication Acceptance Date: June 27, 2002
Publication Date: N/A
Technical Abstract: Background: The emergence of bacterial antimicrobial resistance in both the medical and agricultural fields has become a serious problem worldwide and is an increasing threat to both animal and human health. There is also increasing evidence that the use of biocides (e.g. disinfectants) may contribute to the development of antibiotic resistance, however, information is limited among veterinary bacterial pathogens and the subject remains contentious. The work shown here focuses on bacterial isolates obtained from a veterinary diagnostic laboratory and the evaluation of those bacteria against disinfectants commonly used in animal production. Methods: Eighty-seven pathogenic Escherichia coli isolates originally obtained from neonatal pigs with diarrhea on five farms in Oklahoma were susceptibility tested using broth microdilution methods to two quaternary ammonium chloride based disinfectants and their individual components. The disinfectants tested were P-128 and Quatricide PV-15. The individual components or component mixtures tested were Barquat MB-50, didecyldimethylammonium chloride, benzyldimethyldodecylammonium chloride, benzyldimethyltetradecylammonium chloride, and benzyldimethylhexadecylammonium chloride. Results: Thirteen of 87 isolates (14.9%) showed consistent resistance characteristics with some or all of the individual components that make up the quaternary ammonium chloride based disinfectants evaluated. Eight (9.2%) of these isolates showed low resistance and five (5.8%) of the thirteen isolates showed from low to intermediate resistance to various components. Three of the eighty-eight isolates (3.4%) showed low resistance characteristics with the two quaternary ammonium chloride based disinfectants evaluated. Conclusion: Three isolates showed only low resistance to the disinfectant mixtures, and this result may not be significant. However, the decreased susceptibility shown by many of these isolates to the individual chemical components suggests that the quaternary ammonium chloride based disinfectants may not be totally achieving the goal of a dependable disinfectant, and the efficacy of these disinfectants after prolonged use may be questionable. Therefore, further surveillance is needed to detect bacteria that demonstrate decreased susceptibilities to these and other disinfectants used in animal production.