Assessment and tracking of antimicrobial resistance in Escherichia coli as a one health perspective.

Genomics has emerged as a powerful tool for addressing the global scenario of antimicrobial resistance (AMR) in the world. The chances of strain circulation across diverse ecosystems has led us to understand the situation from one health point of view. The study examined 897 Escherichia coli genomes across healthcare (n = 615), veterinary and fisheries (n = 219), and environment (n = 63) from Gujarat, India, from 2022 to 2025. The genomes were characterized by sequence type (ST), serotype, and phylogroup analysis to identify the dominant clonal lineages. Furthermore, antibiotic resistance genes (ARGs) and plasmids were analyzed to understand the movement of horizontal gene transfer (HGT). The putative transmission events across sectors were identified using single-nucleotide polymorphisms (SNPs) with distance thresholds of 0, 1, 2, 5, 10, 20, and 50. We reported the presence of internationally reported dominant clonal lineage ST131-B2-O25:H4 across all settings. The healthcare isolates carried a heavy burden of ARGs than the environment and veterinary and fisheries sectors (median 9 vs. 5 vs. 1 gene per isolate), which is consistent with the use of clinical antimicrobial use exerting the dominant selective pressure in this dataset. Plasmid clustering identified 505 distinct clusters, of which 64 were detected across all three sectors, carrying acquired resistance genes namely mphA, sul1, blaCMY-59, qnrS1, and tetA on predominantly IncF (IA, IB, IC, II) replicons. Resistance genes and mobile genetic elements (IS3, IS5, and IS66) were classified by co-location confidence. Potential transmission events and co-circulation both within and across niches were indicated by overlapping clusters. Genomic clustering and mobility patterns of plasmids identified in the E. coli strains are consistent with the possible clonal and plasmid-mediated spread from healthcare to the veterinary and fisheries and the environment sectors. This study's convenience-based sampling and cross-sectoral design do not establish confirmed or directional transmission. These findings support a One Health framework for AMR surveillance, prioritizing biosecurity, antimicrobial stewardship, and infection prevention and control across sectors.