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Antimicrobial Use and Antimicrobial Resistance in Ontario Swine Production

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Title: Antimicrobial Use and Antimicrobial Resistance in Ontario Swine Production
Author: Bosman, Angelina Louise
Department: Department of Population Medicine
Program: Population Medicine
Advisor: McEwen, ScottReid-Smith, Richard J.
Abstract: There is a need for information on antimicrobial use (AMU) and antimicrobial resistance (AMR) in swine for the development of good antimicrobial stewardship practices and policies, to meet international reporting obligations, and for research. The objectives of this thesis were to 1) evaluate the understanding of and preferences for AMU metrics by swine veterinarians, 2) to describe and quantify AMU in pigs in Ontario, 3) to investigate associations between the quantity of AMU in nursery herds and environmental, farm management, and disease factors, and 4) to identify associations between AMU and macrolide resistance in enteric Campylobacter spp. from nursery pigs. We surveyed swine veterinarians across Canada and discovered they had a good understanding of AMU metrics, and a preference for dose-based metrics. We collected data on AMU during one production cycle from 25 farrowing and 25 nursery herds in Ontario and obtained matching data from 23 grower-finisher herds from the Canadian Integrated Program for Antimicrobial Resistance Surveillance. We discovered that nursery pigs used the most antimicrobials in milligrams per kilogram and Canadian defined daily doses per 1,000 pig-days (doseCA rate), while grower-finisher pigs used the most antimicrobials in total kilograms and Canadian defined daily doses per pig. There was infrequent use of Health Canada category I antimicrobials, however, ceftiofur was used routinely for disease prevention in some farrowing herds. Using multi-variable linear regression, we identified factors associated with increased AMU in nursery pigs including the spring season (compared to summer), herds reporting a positive E. coli status, and continuous-flow production systems (compared to all-in-all-out), while decreased AMU was associated with herds that supplement feed with zinc above 500 ppm, the fall season (compared to summer), and herds reporting a positive porcine circovirus associated disease status. Using a t-test, we found the mean doseCA rate of chlortetracycline and tiamulin was higher in herds with at least one macrolide resistant Campylobacter isolate. This thesis fills an important gap in Canadian research and provides information helpful for identifying opportunities to improve AMU. It would be useful for future research to compare the results of this thesis with data from other Canadian pig-producing provinces.
Date: 2021-05
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Related Publications: Bosman AL, Deckert AE, Carson CA, Reid-Smith RJ, Poljak Z, McEwen SA. Choosing which metrics to use when reporting antimicrobial use information to veterinarians in the Canadian swine industry. Can Vet J. 2021 May;62(5):453-460. PMID: 33967283; PMCID: PMC8048206; DOI: cvj_05_453 [pii].

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