Multidrug Resistance Dissemination in Escherichia coli Isolated from Wild Animals: Bacterial Clones and Plasmid Complicity

Objectives. Epidemiological data concerning third-generation cephalosporin (3GC) resistance in wild fauna are scarce. The aim of this study was to characterize the genes, their genetic context, and clonal relatedness 17 Escherichia coli resistant 3GC isolated from animals. Methods. isolates were characterized by short-read whole genome sequencing, long-read sequencing used for hybrid assembly plasmid sequences. Results. gene most identified extended-spectrum β-lactamases (ESBL)-encoding blaCTX-M-1 (82.3%), followed blaCTX-M-32 (5.9%), blaCTX-M-14 blaSHV-12 (5.9%). E. mainly belonged sequence types (STs) rarely reported humans. single nucleotide polymorphism (SNP)-based typing showed that genomes animals (wild boars, birds prey, buzzards) formed clusters (<5 SNPs), showing a dissemination crossing species boundaries. blaCTX-M-1-harboring IncI1-ST3 predominant ESBL-encoding (76.4%) animal isolates. Plasmid comparison revealed 110-kb self-transferable consisting conserved backbone two variable regions involved antimicrobial interaction with recipient cells during conjugation. Conclusion. Our results highlighted unexpected blaCTX-M-1-encoding clones complicity spread within fauna.