Antimicrobial use and antimicrobial resistance monitoring for pig production in the United States of America

Monitoring antimicrobial use (AMU) and antimicrobial resistance (AMR) on farms is recognised as an important component of antimicrobial stewardship yet the process can be resource intensive. This paper describes a subset of findings from the first year of a collaboration across government, academia, and a private sector veterinary practice focused on swine production in the Midwestern United States. The work is supported by participating farmers and the greater swine industry. Twice-annual collection of samples from pigs along with AMU monitoring, occurred on 138 swine farms. Detection and resistance of Escherichia coli from pig tissues was assessed, and associations between AMU and AMR were evaluated. This paper describes the methods utilised and the first-year E. coli-related results from this project. Higher minimum inhibitory concentrations (MIC) of enrofloxacin and danofloxacin in E. coli from swine tissues were associated with the purchase of fluoroquinolones. There were no other significant associations between MIC and AMU combinations in E. coli isolated from pig tissues. This project represents one of the first attempts to monitor AMU as well as AMR in both swine and public health pathogens on a large-scale commercial swine system in the United States of America.