Prevalence of antimicrobial resistance (AMR) in fecal Escherichia coli and Enterococcus spp. isolated from beef cow-calf operations in northern California and associations with farm practices

Abstract

Antimicrobials are necessary for treatment of bacterial infec­tions in both humans and animals; however, antimicrobial re­sistance (AMR) is becoming a public health threat. As a result, antimicrobial use in food animals has come under scrutiny. En­terococcus and E. coli are both part of the normal flora of the bo­vine gastrointestinal tract, with the potential to cause disease, and often serve as sentinels for AMR. Studies investigating AMR in cow-calf operations are sparse but are essential for un­derstanding of AMR in the beef industry. The objective of this cross-sectional study was to assess prevalence of AMR levels in E. coli and Enterococcus spp. in beef cattle of different life stages, breeds, pasture type exposure and antibiotic drug exposure on a herd and individual level.