Twenty Years of Disk Diffusion Testing Indicate No Meaningful Loss of Antibiotic Susceptibility for Multiple Pathogens Isolated from Hatcheries Operated by the Idaho Department of Fish and Game

Abstract

AbstractAntibiotic use in animal production, including aquaculture, has become a controversial subject in recent years. It is unclear whether antibiotic use by fish hatcheries or farms is functionally related to the development of resistance in important human pathogens. Nevertheless, antimicrobial resistance is relevant to aquaculture because it may reduce the effectiveness of the limited treatment options available for fish health management. We used linear regression models to explore possible temporal trends in antibiotic susceptibility of several bacterial fish pathogens over a 20‐year period at 12 Idaho Department of Fish and Game (IDFG)‐operated hatcheries. Observed antibiotic susceptibility was variable among hatcheries and among pathogens. Predicted susceptibility was generally unchanged or increased on average over the study period, suggesting no significant loss in susceptibility to the antibiotics tested. Collectively, our results indicate that fish health management, including occasional antibiotic treatment, has not substantively influenced antibiotic susceptibility of pathogens at IDFG‐operated hatcheries.