Emergence and Dissemination of Antimicrobial Resistance in Aquaculture: Mechanisms, Environmental Drivers, and One Health Implications

The exponential growth of the aquaculture sector, driven by the need to meet global food demand, poses significant challenges, particularly the emergence of antimicrobial-resistant bacteria. Antimicrobial resistance (AMR) represents a major public health threat, associated with high mortality rates and a limited pipeline of effective therapeutic agents, while intensive antibiotic use in aquaculture promotes both the selection of resistant bacteria and environmental toxicity. Within the One Health framework, which recognizes the interconnectedness of human, animal, and environmental health, it is critical to clarify the specific role of aquaculture in the emergence and dissemination of AMR. Yet, key gaps remain in the integrated understanding of (i) bacterial communities in aquaculture systems with pathogenic or opportunistic potential, (ii) their association with antimicrobial resistance genes (ARG), and (iii) the mechanisms enabling their transfer across environments. Aquatic systems act as reservoirs of resistance genes that can spread via horizontal gene transfer (HGT), including conjugation, transformation, and transduction. Importantly, the relative contribution of these mechanisms to resistance dissemination within aquaculture and their transmission to humans remains poorly defined. This review critically synthesizes current evidence on the role of aquaculture in AMR spread, focusing on relevant bacterial taxa, the resistance genes they harbor, and their capacity for transfer across species and environments, as well as evaluating evidence of bidirectional transmission between aquaculture systems and humans. This integrative approach identified key issues at the interface of knowledge gaps and thus supports the development of more effective control strategies and antibiotic use within the One Health framework.