Urban trash bins as reservoirs of multidrug-resistant Enterococcus with shared resistance genes across clinical and environmental niches.

Environmental reservoirs of antimicrobial-resistance genes (ARGs) are increasingly implicated in the spread of multidrug-resistant pathogens, yet urban trash bins remain largely unexplored. To address this gap, we sampled 254 public trash bin surfaces and recovered 124 Enterococcus isolates for whole-genome sequencing. An overwhelming 99.2 % of isolates exhibited multidrug resistance, with E. lactis, E. casseliflavus, E. faecalis, and E. faecium predominating. ARG counts among trash-bin isolates did not significantly differ from global water- and soil-derived isolates of the same species; however, individual trash-bin isolates showed high ARG diversity. Two E. faecalis isolates (C166 and C175) harbored the linezolid-resistance gene optrA within conserved resistance islands (erm(A)-optrA-fexA and optrA-fexA-erm(A)-ant(9)-Ia), closely matching arrangements reported in human clinical strains. Phylogenetic analysis, incorporating 18 trash bin, 402 animal, 384 human, 162 environmental, and 122 food-derived isolates from across China, revealed extensive cross-reservoir intermixing. Transmission network analyses (SNPs < 20) further confirmed active participation of trash-bin isolates in multidirectional ARG dissemination, demonstrating direct connections to animal, human, environmental, and food isolates. These results underscore urban trash bins as critical yet overlooked reservoirs and active transmission nodes of multidrug-resistant Enterococcus, highlighting the urgent need for integrated environmental surveillance and targeted interventions within a One Health framework.