Prevalence and Persistence of Ceftiofur-Resistant Escherichia coli in A Chicken Layer Breeding Program

SIMPLE SUMMARY: This is a study associated with the prevalence and persistence of ceftiofur, the third-generation cephalosporin antibiotic-resistant Escherichia coli in a chicken layer breeding farm. Notably, epidemiological studies in poultry have been primarily focused on single breeding periods and may have underestimated the maintenance of the ceftiofur-resistant Escherichia coli in different breeding periods from layer hens. Our results showed that the detection rates of the ceftiofur-resistant Escherichia coli fluctuated across different breeding periods, and the ST101 ceftiofur-resistant Escherichia coli was the most prevalent and persistent sequence type across the breeding periods. This study contextualized ceftiofur resistance in different breeding periods, monitoring which can have important implications for food animals. ABSTRACT: We determined the longitudinal persistence of ceftiofur-resistant Escherichia coli from a chicken breeding farm in China. A total of 150 samples were collected from 5 breeding periods in a flock of layer hens, and the prevalence of ceftiofur-resistant E. coli fluctuated across the 5 chicken breeding stages: eggs, 3.33%; growing period, 100%; early laying period, 36.7%; peak laying period, 66.7% and late laying period, 80%. The most prevalent ceftiofur resistance genes were bla(CTX-M-55), bla(CMY) and bla(NDM), and ST101 was the most prevalent and persistent sequence type across the breeding periods. Our results indicated that this breeder flock was heavily contaminated by ST101 ceftiofur-resistant E. coli and that its presence should be intensively monitored on chicken farms.