Escherichia coli shedding patterns in humans and dogs: insights into within-household transmission of phylotypes associated with urinary tract infections.

Within-household transmission of Escherichia coli may contribute to the pathogenesis of urinary tract infection but understanding of transmission is limited by the lack of longitudinal data on individual shedding patterns. In this study, faecal E. coli was isolated over 6 months from 18 humans and 13 dogs in eight households. Typing 322 E. coli isolates by amplified fragment length polymorphism showed high overall diversity as indicated by the average diversity index (0.66). However, individual shedding patterns varied considerably: two persons carried a single resident E. coli clone throughout the study whereas distinct clones were isolated from other individuals on each sampling time. Nineteen clones were shared within six of the eight households and seven of these clones were shared between humans and dogs. The frequent sharing of clones belonging to phylotypes B2 (n=7) or D (n=4) supports the hypothesis that urovirulent E. coli are transmitted between household members, including dogs, or may be acquired by a common source such as food.