Genomic evidences of gulls as reservoirs of critical priority CTX-M-producing Escherichia coli in Corcovado Gulf, Patagonia

Extended spectrum β-lactamase (ESBL)-producing Enterobacterales has spread rapidly around the world, reaching remote areas. In this regard, wild birds that acquire ESBL producers from anthropogenically impacted areas can become reservoirs, contributing to further dissemination of antimicrobial-resistant bacteria categorized as critical priority pathogens to remote environments, during migration seasons. We have conducted a microbiological and genomic investigation on the occurrence and features of ESBL-producing Enterobacterales in wild birds from the remote Acuy Island, in the Gulf of Corcovado, at Chilean Patagonia. Strikingly, five ESBL-producing Escherichia coli were isolated from migratory and resident gulls. Whole-genome sequencing (WGS) analysis revealed the presence of two E. coli clones belonging to international sequence types (STs) ST295 and ST388, producing CTX-M-55 and CTX-M-1 ESBLs, respectively. Moreover, E. coli carried a wide resistome and virulome associated with human and animal infections. Phylogenomic analysis of global and publicly genomes of E. coli ST388 (n = 51) and ST295 (n = 85) clustered gulls isolates along to E. coli strains isolated from the environment, companion animal and livestock in the United States of America, within or close to the migratory route of Franklin's gull, suggesting a possible trans hemispheric movement of international clones of WHO critical priority ESBL producing pathogens. [Display omitted] •Genomic evidences of gulls as reservoirs of MDR E. coli in Patagonia are presented.•MDR E. coli were isolated from migratory and resident gulls in Chiloé Archipelago.•E. coli sequence types ST295 and ST388 carried clinically relevant blaCTX-M genes.•Phylogenomic relatedness of international ST295 and ST388 lineages is highlighted.•The role of gulls in the spread of AMR into remote environments is discussed.