Environmental resistomes and antimicrobial resistance: integrating the One Health framework.

Antimicrobial resistance (AMR) has emerged as a critical global health challenge, exacerbated by the interconnected dynamics of human, animal, and environmental health systems. The "One Health" approach, which integrates these domains, offers a comprehensive framework for addressing AMR at its roots. This review explores the environmental dimension of AMR by examining the role of environmental microbiomes as reservoirs and transmission vectors of antimicrobial resistance genes (ARGs). It highlights emerging evidence, transmission pathways, detection methodologies, and policy gaps, with an emphasis on low- and middle-income countries (LMICs). An in-depth literature synthesis was conducted across environmental, clinical, and molecular microbiology studies to understand the eco-evolutionary dynamics of resistance, routes of ARG transmission, and effectiveness of current surveillance models. Emphasis was placed on novel detection technologies and integrated policy frameworks. Environmental resistomes present in soil, water, air, and waste play a pivotal yet underappreciated role in ARG dissemination via horizontal gene transfer, mobile genetic elements, and co-selectors like heavy metals and biocides. The complexity of microbial communities in diverse ecological matrices fosters the persistence and evolution of resistance. Current surveillance systems often neglect environmental inputs, particularly in LMICs, limiting the effectiveness of AMR mitigation efforts. A paradigm shift is required to recognize the environmental microbiome as a central component of AMR. Integrated "One Health" strategies, improved environmental surveillance, policy reforms, and novel technological interventions are critical for global AMR control. Bridging the research-policy gap and empowering local surveillance infrastructure can significantly enhance resistance management and public health outcomes.