Escherichia coli causing urinary tract infections in dogs and humans differ in population structure and pathogenic...

To identify host-specific pathogenesis and intraspecies transmission potential of spatiotemporally related Escherichia coli causing human and canine urinary tract infections (UTIs).

We collected 103 unique E coli isolates that caused clinical UTIs from a veterinary and human teaching facility over a 2-year period. Isolates were assessed for antimicrobial resistance and biofilm production and sequenced to compare population structure, functional pathways, and virulence and resistance gene composition.

Humans' E coli were more likely to be from sequence type (ST)-131 and ST95, whereas canine isolates were more likely to be from ST372. Sequence type 73, ST38, and ST12 were composed of equal proportions of human and canine isolates. Escherichia coli from both humans and canines were significantly enriched in different functional pathways that promote colonization of the urinary tract. Canine isolates carried a more robust virulome (β, 14.3; 95% CI, 5.8 to 22.9) that was enriched in many virulence genes and had greater biofilm production (OR, 2.91; 95% CI, 1.24 to 6.81). Human isolates carried a more abundant resistome (Incidence Risk Ratio [IRR], 1.69; 95% CI, 1.31 to 2.18) that conferred reduced susceptibility to multiple drug classes.

Urinary-associated E coli from different hosts are composed of unique strain populations that harbor different functional, virulence, and resistance capacities. Escherichia coli from ST73, ST38, and ST12 can cause infections in both species, suggesting potential for cross-species transfer.

Our findings contribute to a broader understanding of E coli UTIs in dogs, how they differ from human infections, and the risk for cross-species transmission of specific E coli subgroups.