Genomic analysis of the zoonotic ST73 lineage containing avian and human extraintestinal pathogenic Escherichia coli (ExPEC)

Extraintestinal pathogenic Escherichia coli (ExPEC) is a globally distributed pathogen, with uropathogenic E. coli (UPEC) and sepsis-associated E. coli (SEPEC) pathotypes particularly involved in human and companion animal disease, while avian pathogenic pathotype (APEC) severely impact poultry health and production. Similarities between APEC from poultry/meat and human ExPEC suggest that some APEC lineages may have zoonotic po-tential. ExPEC sequence type 73 (ST73) and its clonal complex (CC) are increasing causes of urinary tract in-fections and sepsis, but its role in zoonotic disease is less well understood. Here, we analyzed the genome sequences of 25 E. coli isolates from Brazil (11 APEC and 14 UPEC) from two time periods, from poultry pro-ducing areas and hospitals in the same geographical regions. Isolates were compared to 558 publicly available ST73/CC73 global sequences. Brazilian APEC harbored virulence factors associated with UPEC/SEPEC such as sfa, cnf1, vat, usp, hlyA, iron acquisition and protectins/serum resistance systems, while lacking some common APEC markers and widespread multidrug resistance. Analysis of core genome MLST and SNP phylogenetic trees indicated evolutionary relationships between subgroups of the Brazilian APEC to two contemporary Brazilian UPEC isolates from the same region, and one Brazilian UPEC available from another study. Phylogenies showed a non-host, geographical, or pathotype specificity, with APEC isolates clustering closely with international human UPEC, SEPEC. The remaining Brazilian UPEC grouped within human clusters. Collectively, this suggests a zoo-notic potential for subgroups of Brazilian APEC from the ST73 lineage that could contaminate poultry products and subsequently cause human infection.