The Public Health Agency of Canada’s (PHAC) Canadian Integrated Program for Antimicrobial Resistance Surveillance (CIPARS) has conducted antimicrobial resistance (AMR) surveillance in cattle entering packing plants and retail beef since the mid-2000s. The surveillance of antimicrobial use (AMU) and resistance in feedlot cattle started in 2019. Given that PHAC is primarily focused on human health, its surveillance efforts are directed toward AMR in bacteria found in the intestinal tracts of both livestock and humans (e.g., E. coli, Campylobacter, Enterococcus). However, feedlots use antimicrobials to combat veterinary pathogens, including the normally commensal bacteria involved in bovine respiratory disease (BRD). Understanding the prevalence of and trends in antimicrobial resistance in BRD-associated bacteria is critical to informing responsible antimicrobial stewardship in feedlot animal health programs.
- Provide representative national estimates of AMU and AMR in the Canadian finishing feedlot sector.
- Monitor trends in AMU and AMR over time and in the context of changes to veterinary practice.
- Assess the potential risks associated with AMU in feedlots on the effectiveness of antimicrobials in animals and humans.
What they did
Feedlots were enrolled by participating veterinary clinics according to particular inclusion criteria and a pre-specified sampling frame. Enrolled feedlots were de-identified by their clinic and assigned a unique code, which was used to link data or samples submitted from that operation.
With respect to the BRD component of the project, deep nasal swabs (deep guarded nasopharyngeal) samples were collected in every surveillance year from 16 animals in each of the enrolled feedlots at entry processing and then again at re-handling. The same pen of cattle (though not necessarily the same individual animal) was sampled at both time points. Samples were transported by courier in an insulated cooler to the Prairie Diagnostic Services (PDS) laboratory in Saskatoon for the culture and identification of Mannheimia haemolytica, Pasteurella multocida and Histophilus somni. Recovered bacterial isolates were tested for sensitivity to a standard panel of antimicrobial drugs.
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