On-Farm Implementation of an Integrated Antimicrobial Stewardship Model in Pig Production: Effects on Antimicrobial Use and Resistance

This study evaluated a 6-month, on-farm antimicrobial stewardship model integrating veterinary oversight, appropriate antimicrobial use, enhanced biosecurity, and an all-in/all-out system on five Korean pig farms lacking prior oversight. Antimicrobial usage and resistance of Escherichia coli were compared before and after implementation. The number of antimicrobial prescriptions decreased significantly following the implementation of the model (from 15.2 ± 9.2 to 7.2 ± 4.7). After model implementation, prescriptions for suckling piglets decreased from 2.2 ± 1.6 to 0.4 ± 0.9, and for weaned piglets from 4.4 ± 2.4 to 1.8 ± 1.1. Overall antimicrobial resistance decreased following model implementation, with the largest decreases were observed in ciprofloxacin (from 57.3% to 21.9%), nalidixic acid (from 60.0% to 34.2%), and cefazolin (from 92.0% to 64.4%). The multidrug-resistance rates in eight antimicrobial classes decreased significantly across all stages (from 28.0% to 4.1%), with decreases for suckling piglets (from 33.3% to 7.1%), weaned piglets (from 40.0% to 0.0%), growers (from 26.7% to 0.0%), finishers (from 26.7% to 14.3%), and sows (from 13.3% to 0.0%). The model effectively reduced both antimicrobial use and resistance, supporting its value for antimicrobial stewardship in pig production.