Is Antimicrobial Resistance in the Microbiome of Food Fish Reversible? 

Project: Research

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Antimicrobial resistance (AMR) has been identified by the World Organization for Animal Health (OIE), World Health Organization (WHO) and the UN General Assembly as one of the most critical issues facing modern medicine. One of the suspected drivers of AMR in veterinary medicine is bacterial exposure to sub-therapeutic levels of antibiotics, resulting in the genetic selection of resistance genes. Some veterinary practices, such as administering antibiotics at low doses to enhance growth, have been identified as problematic for AMR selection and are no longer practiced in many countries. However, antibiotic resistance is still on the rise. It is possible that other practices, such as metaphylactic applications of antibiotics, also select for MR; however, the underlying mechanisms for metaphylactic treatments driving AMR have not been fully explored, especially in aquaculture systems. Further, no one has evaluated whether this selection pressure is dependent on the half-life of the antibiotics used or whether the process is reversible. The answers to both of these questions are important for veterinarians to implement prudent use of antibiotics on fish farms. The proposed project will assess whether metaphylactic antibiotic treatment in food fish results in sub-therapeutic antibiotic tissue levels in the animals, whether it changes the diversity and the resistome profile of the fish’s gut microbiome, whether these phenomena occur across antibiotics with different half-lives, and whether any genetic and phenotypic changes are reversed post treatment. This project will provide the foundation for the development of evidence-based treatment strategies that minimize the risk of AMR associated with exposure to therapeutic and sub-therapeutic antibiotic levels, and improve treatment efficacy in aquaculture settings. The long-term impacts of this research are likely to be far-reaching, given the growth of global aquaculture and our current lack of knowledge of best practices to minimize AMR in aquatic ecosystems. 


Project number9043115
Grant typeGRF
Effective start/end date1/01/22 → …