Antimicrobial Usages and Antimicrobial Resistance in Commensal Escherichia coli From Veal Calves in France: Evolution During the Fattening Process

Conclusion Our study has shown that ESBL-producing E. coli from the subdominant flora were on a decreasing trend in veal calves in 10 unrelated fattening farms, pointing out that those animals had most likely been contaminated beforehand during their first days of life. While pressure to decrease antibiotic use have to be maintained in fattening farms, our study showed that even more efforts have to be put in the farms of origin of the veal calves, in order to further decrease the number of ESBL-positive individuals entering the fattening process. In parallel, levels of resistances to non-critically important antimicrobials in bacteria from the dominant flora were already high upon arrival but have still further increased over time until slaughter. Consequently, our study also clearly highlighted that if only ESBL-producing isolates from the subdominant flora were monitored, it might have led to a partial (and partly false) picture of AMR rates globally decreasing during the fattening period. These results should promote surveillance systems not only relying on a single AMR indicator (such as the prevalence of ESBL-producers) but, where possible, to implement a more global approach of AMR monitoring. Author Contributions EG, MH, and J-YM designed the experiments and analyzed the data. CM supervised the sampling campaign. MB, GC, EG, and NJ performed the experiments. MH and EG drafted the manuscript. J-YM actively contributed to the manuscript’s writing. All authors ...
Source: Frontiers in Microbiology - Category: Microbiology Source Type: research