Submitted to: National Foundation for Infectious Disease
Publication Type: Abstract Only
Publication Acceptance Date: June 24, 2003
Publication Date: N/A
Technical Abstract: Background: The emergence of bacterial antimicrobial resistance has become a serious problem worldwide to both animal and human health. There is evidence that the use of biocides may contribute to the development of antibiotic resistance; however, information on disinfectant susceptibilities is limited among veterinary bacterial pathogens. Methods: Eighty-nine enterotoxigenic Escherichia coli isolates were tested for susceptibility to chlorhexidine digluconate using broth microdilution techniques. Data were compared to ribogroup, virulence factor genotypes, and antibiotic resistance phenotypes. Results: Forty-four percent of the isolates showed decreased susceptibility to chlorhexidine (MICs of 2, 4, and 8 times the JM-109 control, with 5.6%, 25.8% and 12.4% of the isolates, respectively). Most (26 of 39) of the chlorhexidine resistant isolates clustered in one ribogroup, however, 7 of the 19 ribogroups contained at least one chlorhexidine resistant isolate. Decreased susceptibility correlated with four virulence factor genotypes (STA, STB, SLT2 and F107). Most of these isolates were also resistant to six antibiotics, but the isolates did not correlate to any specific antibiotic resistance phenotype. Conclusion: Correlation of chlorhexidine resistance to ribogroups and to the presence of virulence factors suggests that the use of disinfectants may select for enterotoxigenic strains of E. coli. Further surveillance is suggested to study potential genetic links between disinfectant resistance and virulence and to improve the knowledge base of resistance traits, virulence and antibiotic resistance of disinfectants.