Antimicrobial Resistance Among Escherichia coli Isolated from Veal Calf Operations in Pennsylvania

Antimicrobial resistance (AR) is a pressing public health concern, and agricultural operations such as dairy and beef cattle production have been implicated as potential sources of resistant bacteria or genetic elements. This study aimed to determine the prevalence of antimicrobial-resistant Escherichia coli from calf pens in 6 auction houses (56 manure composite samples) and 12 veal calf operations (240 fecal samples in 2 visits: after the calves arrived at the farm and shortly before the animals were sent to slaughter) in the Commonwealth of Pennsylvania. A total of 1567 generic E. coli were isolated and screened for resistance phenotypes. Resistant E. coli were isolated from all auction houses and farms sampled. Based on nonparametric Kruskal-Wallis tests, incremental prevalence of E. coli resistant to ampicillin, azithromycin, cefoxitin, ceftiofur, ceftriaxone, chloramphenicol, streptomycin, sulfisoxazole, trimethoprim-sulfamethoxazole, and tetracycline in the samples from auction houses and the first and second farm visits was observed (χ 6.98-15.91, p