Persistence and transmission of multidrug resistant Escherichia coli is driven by recycling between different animal groups, including wild birds, on a farm with low antimicrobial usage.. ARDIG: Persistence and transmission of MDR E. coli is driven by recycling between different animal groups, including wild birds, on a farm with low antimicrobial usage.

Antimicrobial resistance (AMR) is a globally recognised threat, with the One Health approach to tackling spread of AMR highlighting importance of studies on the dynamics of AMR gene spread and persistence in human, animals and their environment. In this study short and long-read whole-genome sequencing (WGS) were used in place of a metagenomics approach, to enable tracking of specific Escherichia coli strains to identify associated AMR genes and mobile elements, over one year on a UK outdoor pig farm with low antimicrobial usage. Our results showed although low levels of AMR E. coli present were on this farm, those that were present were likely to be multi-drug resistant (MDR) E. coli of particular sequence types (STs), with shared clones showing epidemiological linkage between pigs of different age class, and pigs and wild bird populations. Possible transmission and recycling of MDR E. coli clones within animal groups drove persistence in the on-farm environment in absence of selective pressure from antimicrobials. While previous studies highlighted horizontal transmission of plasmids driving AMR spread, our study showed limited evidence of plasmid spread between E. coli STs, with non-conjugable plasmids identified as remaining associated with individual ST populations, and often integrated within the chromosome.