Genotypic and phenotypic comparison of Escherichia coli from uterine infections with different outcomes: clinical metritis in the cow and pyometra in the bitch.

Escherichia coli uterine infection originates different clinical outcomes in the canine and bovine species. Here, E. coli strains isolated from bovine clinical metritis and canine pyometra cases were analyzed by PFGE, screened for 33 virulence factor (VF) genes and for phylogenetic grouping. Bovine and canine E. coli isolates presented a low degree of genetic similarity. Canine E. coli strains belonged to phylogenetic group B2 and presented a high number of VF genes, whereas bovine E. coli strains belonged to phylogenetic groups B1 and A and had a low number of VF genes. In conclusion, E. coli strains isolated from cow clinical metritis had a low potential of virulence. In contrast, bitch pyometra E. coli isolates had a high virulence potential, which might be relevant in the pathogenesis of pyometra. These differences between canine and bovine E. coli isolates may partially explain the different outcomes of the uterine infection in the two species.