Molecular characterization and antimicrobial resistance of faecal and urinary Escherichia coli isolated from dogs and humans in Italy.

During this study, 109 faecal Escherichia coli samples isolated from 61 dogs and 48 humans were characterised according to phylogenetic group, extraintestinal virulence factors and antibiotic resistance. The isolates from dogs were predominantly distributed within phylogroup B1 (36%), while the majority of human strains belonged to phylogroup B2 (54%). The prevalence of cnf1, hlyA, papC and sfa virulence genes was significantly associated with the group B2. Canine isolates showed multidrug resistance (MDR) more frequently than human strains. Since group B2 contains most of the strains that cause extraintestinal infections, all 46 B2 faecal strains were confronted against an addition population of 57 urinary E. coli strains belonging to the same phylogroup. The comparison shows that there was no significant difference in the occurrence of virulence factors or in the distribution of antibiotic resistance between faecal and urinary E. coli isolates from dogs. At the same time, a highly significant association was detected between multiple resistance and the source of the strains and between MDR and E. coli isolated from urine in human. This study highlighted similar features of E. coli isolated across sources and hosts. The data suggest a high prevalence of antibiotic resistance in faecal strains, which may represent a serious health risk since these strains can function as a reservoir for uropathogenic E. coli.