Do Cattle Bacteria Contribute to Antibiotic Resistance in Human Medicine?

This article written by Dr. Reynold Bergen, BCRC Science Director, originally appeared in the November 2020 issue of Canadian Cattlemen magazine and is reprinted on the BCRC Blog with permission of the publisher.

E. coli live in the digestive tracts of warm-blooded animals and birds. Most are harmless, some are beneficial, and some (like E. coli O157:H7) can be very dangerous. E. coli are also involved in antibiotic resistance.

“Extended-spectrum beta-lactamase producing” (or ESBL) E. coli are a major concern in human medicine. These bacteria are resistant to many antibiotics used in both human and veterinary medicine. Ordinary E. coli can cause urinary tract or bloodstream infections in people. They’re usually quite easy to treat with antibiotics. But if ESBL E. coli are responsible, the infection can’t be easily treated with antibiotics, and the illness can be much worse or even fatal.

E. coli rarely causes disease in feedlot cattle. But ESBL E. coli are still a concern, because antibiotic resistance genes are often located on “mobile genetic elements” that bacteria can trade with each other, even with completely unrelated bacteria. So antibiotic resistant BRD bacteria like Mannheimia, Pasteurella or Histophilus can spread their antibiotic resistance genes to each other, or possibly to E. coli. That’s like a border collie developing horns after a day of herding Herefords. Continue reading

Does Antibiotic Resistance Move Through the Environment?

This article written by Dr. Reynold Bergen, BCRC Science Director, originally appeared in the December 2018 issue of Canadian Cattlemen magazine and is reprinted on the BCRC Blog with permission of the publisher.


Recent columns have talked about antibiotic use in Canadian cow-calf and feedlot operations. Contrary to common misconceptions, antibiotic resistant bacteria are very unlikely to transfer from cattle to beef, evade food safety interventions in the processing plant, survive cooking, and cause an antibiotic resistant infection in a person. But can antibiotic resistant bacteria be transmitted from cattle, through feedlot manure and runoff, across soil, through wetlands, streams and rivers, and reach humans through the environment?

A Beef Science Cluster study led by Dr. Rahat Zaheer and Tim McAllister of Agriculture and Agri-Food Canada (with collaborators from the Public Health Agency of Canada, the University of Calgary’s faculties of medicine and veterinary medicine, University of Guelph, Alberta Agriculture and Feedlot Health Management Services) examined this question.

What they did: This research focused on bacteria called enterococci that can cause infections in humans (e.g. urinary tract, liver and bile duct, heart, surgery wound, and bloodstream infections). Most enterococcal infections can be effectively treated with macrolide antibiotics. This is important because macrolides (products like Draxxin, Zuprevo, Micotil, Tylan, Zactran, etc.) are commonly used in both beef production and human medicine.

Over a two-year period, this team collected samples from feedlots (pen floor fecal samples, collection ponds, stockpiled and composted manure), agricultural soils, wetlands, streams, municipal sewage, packing plants, retail meats and human patients. Advanced lab testing was used to identify the specific types of enterococci and antibiotic resistance patterns in the samples from each location.

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