Genomic and Phenotypic Analysis of an ESBL-ProducingE. coliST1159 Clonal Lineage From Wild Birds in Mongolia

Background In addition to the broad dissemination of pathogenic extended-spectrum beta-lactamase (ESBL)-producingEscherichia (E.) coliin human and veterinary medicine and the community, their occurrence in wildlife and the environment is a growing concern. Wild birds in particular often carry clinically relevant ESBL-producingE. coli. Objectives We analyzed ESBL-producing and non-ESBL-producingE. coliobtained from wild birds in Mongolia to identify phylogenetic and functional characteristics that would explain the predominance of a particularE. coliclonal lineage in this area. Methods We investigated ESBL-producingE. coliusing whole-genome sequencing and phylogenetics to describe the population structure, resistance and virulence features and performed phenotypic experiments like biofilm formation and adhesion to epithelial cells. We compared the phenotypic characteristics to non-ESBL-producingE. colifrom the same background (Mongolian wild birds) and genomic results to publicly available genomes. Results and Conclusion We found ESBL-producingE. colisequence type (ST) 1159 among wild birds in Mongolia. This clonal lineage carried virulence features typical for extra-intestinal pathogenic or enterotoxigenicE. coli.Comparative functional experiments suggested no burden of resistance in the ST1159 isolates, which is despite their carriage of ESBL-plasmids. Wild birds will likely disseminate these antibiotic-resistant pathogens further during migration.