ESBL-E. coli prevalence in seabirds from the Southeast Pacific Coast

Antimicrobial resistance (AMR) is a major global public threat, now largely reported in natural environments. Seabirds are carriers of extended-spectrum ß-lactamase-producing Escherichia coli (ESBL-E. coli). Different foraging and breeding behaviour among seabirds could impact ESBL-E. coli prevalence and its genetic background. We compared the prevalence and genetic determinants of ESBL-E. coli from the resident Kelp gull (Larus dominicanus, Ld), the migratory Franklin's gull (Larus pipixcan, Lp), and the endemic Peruvian pelican (Pelecanus thagus, Pt) from the Humboldt Current Ecosystem (HCE) of central Chile. From 2020 to 2022, we collected 699 fresh faecal samples (Ld=449, Lp=116, Pt=134), and isolated 271 ESBL-E. coli (39%). Whole-genome-sequencing was performed on 5683 E. coli selected isolates to identify their Sequence Types, AMR genes, virulence genes, mobile genetic elements (MGE), and assess potential interspecies transmission.