Successful Dissemination of Plasmid-Mediated Extended-Spectrum β-Lactamases in Enterobacterales over Humans to Wild Fauna.

Background: The emergence of multidrug-resistant bacteria remains poorly understood in the wild ecosystem and at the interface of habitats. Here, we explored the spread of containing IncI1-ST3 plasmid encoding resistance gene () in human-influenced habitats and wild fauna using a genomic approach.

Methods: Multilocus sequence typing (MLST), single-nucleotide polymorphism comparison, synteny-based analysis and data mining approaches were used to analyse a dataset of genomes and circularised plasmids.

Results: CTX-M-1 sequence types (STs) were preferentially associated with ecosystems. Few STs were shared by distinct habitats. IncI1-ST3- plasmids are disseminated among all phylogroups. The main divergences in plasmids were located in a shuffling zone including inserted in a conserved site. This insertion hot spot exhibited diverse positions and orientations in a zone-modulating conjugation, and the resulting synteny was associated with geographic and biological sources.

Conclusions: The ecological success of IncI1-ST3- appears less linked to the spread of their bacterial recipients than to their ability to transfer in a broad spectrum of bacterial lineages. This feature is associated with the diversity of their shuffling conjugation region that contain . These might be involved in the resistance to antimicrobials, but also in their spread.