Transmission patterns of multiple strains producing New Delhi metallo-β-lactamase variants among animals and the environment in live poultry markets

The widespread transmission of bla NDM among livestock and the live poultry industry attracts considerable public attention. However, studies have not yet addressed its impact on public health in live poultry markets (LPMs). Herein, we investigated the prevalence and genomic epidemiology of bla NDM -positive bacteria in various niches, and explored the transmission patterns of bla NDM within LPMs. Samples were collected between 2019 and 2022 from two LPMs in China. bla NDM was most prevalent in wastewater (35/66, 53.03%). All vegetable samples were negative for bla NDM . bla NDM was mainly distributed among Escherichia coli (266/336, 79.17%), Klebsiella pneumoniae (62/336, 18.45%), and Acinetobacter baumannii (3/336, 0.89%). Some novel hosts, including Pseudomonas monteilii and Pseudomonas otitis , were also identified. Diverse variants bla NDM-1 , bla NDM-5 , bla NDM-9 , bla NDM-13 , and bla NDM-27 were identified. The bla NDM -positive E. coli ST2659 was dominant. bla NDM was found to coexist with mcr-1 (4/51, 7.84%). Horizontal gene transfer plays a vital role in bla NDM transmission within the LPMs. Some bla NDM -harboring clones transfer among animals and the environment through the food chain and close contact. More efforts are needed to curb the transmission trend of bla NDM among humans, animals, and the environment within LPMs.