In another study on antibiotic resistance and colibacillosis in broiler chicken in Québec, Patrick Boerlin and his collaborators demonstrated that spectinomycin and gentamicin resistance genes were located on the same mobile genetic element in avian pathogenic E. coli. This provided a likely explanation for the recent surge of gentamicin resistance observed by the provincial diagnostic laboratory in this province (Chalmers et al., 2017) despite the absence of gentamicin use.
These studies demonstrate that although the restrictions in the use of critically important antibiotics have positive effects, bacteria resistant to these agents are still lingering in the gut of chicken and that other less important antibiotics present the potential to maintain and possibly even increase their prevalence. Efforts to continuously improve and adjust our use of antibiotics in animals are definitely warranted.
- Zhang P. L. C. 2017. Resistance to extended-spectrum cephalosporins in Enterobacteriaceae from chickens, dogs, and pigs in Ontario. MSc thesis, University of Guelph.
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- Martin L. C., Weir E. K., Poppe C., Reid-Smith R. J., Boerlin P. 2012. Characterization of blaCMY-2 plasmids in Salmonella and Escherichia coli isolates from food animals in Canada. Appl Environ Microbiol. 78:1285-7.
- Chalmers G., Cormier A. C., Nadeau M., Côté G., Reid-Smith R. J., Boerlin P. Determinants of virulence and of resistance to ceftiofur, gentamicin, and spectinomycin in clinical Escherichia coli from broiler chickens in Québec, Canada. Vet Microbiol. 2017 203:149-157.