National surveillance of antimicrobial use and antimicrobial resistance in Canadian feedlots

Abstract

There is public demand for the demonstration of responsible antimicrobial stewardship, especially in the livestock sector. Surveillance can detect temporal trends in antimicrobial use (AMU) and antimicrobial resistance (AMR) that identify emerg­ing issues and research priorities, support stewardship goals, and meet the growing demand for reliable data. In this project, inclusion/exclusion criteria were used to define and randomly enrol eligible feedlots in proportion to feedlot capacity and the number of fed cattle in target provinces. Data was abstracted from both veterinary dispensing and AMU records from ran­domly sampled production lots closed in the previous calendar year. Composite fecal samples were collected yearly from ran­domly selected pens of cattle within 30 days of slaughter. Fecal culture identified Escherichia coli, Salmonella spp., Campylobacter spp. and Enterococcus spp.; recovered isolates were subject to antimicrobial susceptibility testing (AST) via broth microdilu­tion. Deep-guarded nasopharyngeal (NP) samples were also collected yearly from individual animals at feedlot entry and subsequent re-handling. Sample culture was performed to iden­tify Mannheimia haemolytica, Pasteurella multocida and His­tophilus somni, and recovered isolates were subject to AST as described above. Integration of longitudinal surveillance data provides a more comprehensive picture of AMU and AMR in the finishing feedlot sector over time