Understanding Antibiotic Treatment Failures in Salmon Aquaculture

Antibiotic treatment failure can occur due to several reasons. In this paper, we summarise our research in Chile and review relevant literature to identify the issues that result in antibiotic treatment failure. The four basic issues we have found for explaining treatment failure include misdiagnoses, resistance, subtherapeutic antibiotic tissue concentrations in target organs, and insufficient treatment time for the elimination of the pathogen at the individual and population levels. Our hypotheses are based on salmonid aquaculture systems but likely apply to other aquaculture industries that use in-feed antibiotic treatments for bacterial infections. It is important to better understand the specific causes of treatment failure as they result in repeated treatments and increased pathogen exposure to subtherapeutic antibiotic levels. Both of these phenomena could increase the risk of antibiotic resistance over time.