Contig-Resolved Genetic Context of Antimicrobial Resistome in Sediments of Two Contrasting Wastewater-Impacted Rivers

River sediments harbor diverse antimicrobial resistance (AMR) determinants; however, gene abundance alone provides limited insight into their genomic context, mobility potential, and associated bacterial hosts. This study employed an assembly- and read-mapping metagenomic framework to surface-sediment metagenomes (40.78 Gb clean data) from two contrasting wastewater-impacted Indian rivers, Adyar (Chennai) and Musi (Hyderabad), retaining sample-, contig- and open reading frame level provenance. ARG-carrying contigs (ACCs; n = 2,402) were annotated for mobile genetic elements (MGEs), biocide/metal resistance genes (BMRGs), virulence factor genes (VFGs), nitrogen-cycling genes (NCycGs), and putative host taxonomy. The resistomes exhibited substantial diversity (264 ARG subtypes) and spatial heterogeneity, with subtype richness in the Adyar (up to 171 subtypes) than in the Musi, where richness progressively declined downstream. Rank IV determinants dominated ARG abundance (77.82%), whereas Rank I determinants accounted for only 9.89%. MGEs were detected on just 3.12% (75/2,402) of ACCs, predominantly comprising plasmid-like contigs and proximal ARG-MGE associations. Co-occurrence with BMRGs was observed on 386 ACCs, whereas VFGs were uncommon (26 ACCs) and primarily represented dual-annotated efflux and envelope-integrity determinants rather than independent virulence loci. NCyc annotations were sparse (12 ACCs), with no evidence of complete nitrification or denitrification pathways. Taxonomic classification resolved 217 ACCs to the species level, with no matches to curated human pathogenic bacteria. Only two Acinetobacter-assigned ACCs exhibited both genus-level pathogenicity and mobility evidence. These findings highlight the importance of integrating mobility and host-taxonomic information to distinguish baseline environmental resistance from potential priorities for AMR surveillance.