Urinary and faecal Escherichia coli O-sero-groups in symptomatic urinary-tract infection and asymptomatic bacteriuria.

The degree of correspondence between urinary and faecal Escherichia coli O-groups has been assessed in non-pregnant women with symptomatic urinary-tract infection or asymptomatic bacteriuria. In 20 of 26 patients with symptomatic urinary tract infection E. coli of the same O-groups as that of the urinary infecting strain was also present in the patient's faecal flora of only five of 25 patients with asymptomatic bacteriuria. This finding indicates that the majority of episodes of symptomatic urinary tract infection in non-pregnant women are not preceded by a significant period of asymptomatic bacteriuria. E. coli O6 showed correspondence between urinary and faecal isolates more frequently than did other O-groups, but it had a relatively low prevalence in the faecal flora of patients with urinary-tract infection caused by E. coli of other O-groups. This finding lends support to previous suggestions that E. coli O6 may be especially pathogenic for the urinary tract.