Antimicrobial Stewardship: A One Health approach with a focus on antimicrobial reduction in dairy cattle
Antimicrobial resistance (AMR) is considered one of the greatest threats facing humanity. Without intervention, AMR impacts are expected to be substantial, compromising human, animal, environmental health. The complex interplay of contributing factors highlights the need for a One Health approach in AMR mitigation. Improving antimicrobial stewardship (AMS) is an integral component of AMR mitigation success. Therefore, thesis objectives included: 1) describe the current state of AMR knowledge in Canada available in the literature, and identify the gaps in our understanding; 2) identify perspectives of AMS, including perceived drivers and barriers across the One Health spectrum of relevant Canadian professionals; 3) focus on the dairy industry as an example where AMS efforts are possible through selective dry cow therapy (SDCT); and 4) describe current SDCT uptake and related practices in the Canadian dairy industry.
Current limitations in the understanding of AMR in Canada are described through a comprehensive review focussed on: 1) treatment optimization; 2) surveillance of antimicrobial use (AMU) and AMR; and 3) prevention of transmission of AMR. Whereas identified barriers to AMS described by Canadian professionals included: 1) lack of various prescribing and AMU support mechanisms; 2) shift in prescriber attitudes to drive change; and 3) stronger economic considerations to support shifting prescribing practices.
Barriers to AMS success described by Canadian professionals included: 1) lack of various prescribing and AMU support mechanisms; 2) shift in prescriber attitudes to drive change; and 3) stronger economic considerations to support shifting prescribing practices. Existing drivers of AMS fell under the themes of 1) guidance to lead change; 2) education to support optimizing AMU; and 3) research to identify best practices and opportunities for action. In response to multiple questions, two cross-cutting themes emerged including: 1) a One Health understanding of AMS, and 2) blaming others for a lack of AMS success. Overall, both sector-specific and cross-sectoral AMS drivers and barriers were identified.
Selective dry cow therapy, only treating cows who could benefit from antimicrobials at drying off, represents an opportunity to reduce AMU in the dairy industry. A narrative review was conducted summarizing available literature regarding SDCT impacts on udder health, milk production, economics, AMU motivations, and AMR. An observational study was also conducted utilizing 2 in-person questionnaires between July 2019 and September 2021 on 144 Canadian dairy farms. Overall, 31% reported adopting SDCT, with approximately 50% less intramammary AMU at drying off compared to treating all cows. A slight majority of farms (56%) applied teat sealants (TS) to all cows at drying off, whereas 12% used TS selectively, and 32% did not use TS. Results highlighted the variability in antimicrobial and TS use protocols at drying off on Canadian dairy farms, and the potential for further AMU reduction with increased SDCT adoption.
Dr. Kayley McCubbin received her Doctor of Veterinary Medicine degree from the Atlantic Veterinary College in 2017, before completed her Masters of One Health at The Royal Veterinary College and The London School of Hygiene & Tropical Medicine in London, England with fieldwork in rural Uganda. In May, Kayley completed her PhD at the University of Calgary focusing on antimicrobial resistance and stewardship from a One Health approach. In addition to her Ph.D. work, Kayley was the Regional Project Manager for the Alberta component of the Canadian Dairy Network for Antimicrobial Stewardship and Resistance, a project coordinator for the AMR – One Health Consortium, and is now the Project Manager for the Alberta One Health AMR Framework for Action through One Health at UCalgary.
