Escherichia coli ST117: Exploring the zoonotic hypothesis

Extraintestinal pathogenic Escherichia coli (ExPEC) can lead to severe infections, with additional risks of increasing antimicrobial resistance rates. Genotypic similarities between ExPEC and avian pathogenic E. coli (APEC) support a possible role for a poultry meat reservoir in human disease. Some genomic studies have been done on the ST117 lineage which contaminates poultry meat, carries multidrug resistance, can be found in the human intestinal microbiota, and causes human extraintestinal disease. This study analyzed the genomes of 61 E. coli from Brazilian poultry outbreaks focusing on ST117, to further define its possible zoonotic characteristics by genotypic and phylogenomic analyses, along with 1,699 worldwide ST117 isolates originating from human, animal, and environment sources. A predominance of ST117 were detected in the Brazilian isolates (n=20/61) frequently carrying resistance to critical antibiotics (>86%) linked to IncFII, IncI1 or IncX4 replicons. High similarities were found between IncX4 from Brazilian outbreaks and those from E. coli recovered from imported Brazilian poultry meat and human clinical cases. The ST117 phylogeny showed non-specificity according to host and continent and an AMR index score indicated highest resistance in Asia and South America, with the latter statistically more resistant and overrepresented with resistance to extended-spectrum beta-lactamases (ESBL). Most ST117 human isolates were predicted to have a poultry origin (93%, 138/148). In conclusion, poultry is a likely source for zoonotic ExPEC strains, particularly the ST117 lineage, which can also serve as a reservoir for resistance determinants against critical antibiotics encoded on highly transmissible plasmids.