Phylogroups, virulence factors, and antimicrobial susceptibility of uropathogenic Escherichia coli isolates from dogs at a veterinary hospital in southern Brazil

Escherichia coli , besides being an important commensal of the intestinal microbiota, can cause infections in different sites in humans and domestic animals. There has been an increasing frequency of multidrug-resistant strains, and in light of this, the present study aimed to characterize antimicrobial resistance profiles, virulence genes, and phylogenetic groups of E. coli isolates from urinary tract infections in dogs. Between 2015 and 2020, a total of 23 E. coli strains were isolated from the urine of 22 dogs with urinary tract infection. Antimicrobial susceptibility testing was performed using the disk diffusion method according to CLSI guidelines. Virulence genes, pathogenicity islands, and phylogenetic groups were determined by polymerase chain reaction (PCR). A high prevalence of multidrug-resistant strains was observed, corresponding to 69.57% of the isolates. Among the virulence factors, fyuA showed the highest prevalence (52.17%), while iroN was detected in 43.48% of canine isolates. The other genes studied, iutA , iss , ompT , and hlyF , were present in 34.78%, 26.09%, 21.74%, and 17.39% of the isolates, respectively. Regarding Clermont phylogenetic classification, group B2 was the most frequent phylogroup (39.13%) among the urinary E. coli isolates from dogs. E. coli isolates from dogs with urinary tract infections showed high frequencies of multidrug resistance, important virulence genes, and predominance of Clermont phylogenetic group B2. These findings suggest the circulation of potentially virulent and multidrug-resistant ExPEC strains among companion animals and emphasize the need for continuous antimicrobial resistance monitoring in veterinary medicine.