Virulence characteristics of Escherichia coli causing first urinary tract infection predict risk of second infection.

Escherichia coli causes most urinary tract infections (UTIs) in ambulatory populations. Several bacterial virulence factors occur more frequently among urinary E. coli isolates than among fecal isolates, but none have been reported to predict risk of second UTIs. DNA hybridization was used to characterize the bacterial virulence profiles of urinary E. coli isolates from 174 women with first UTI and compared for risk of second UTI. Of the women, 28 (16%) had a culture-confirmed second UTI within 6 months of a negative test-of-cure. Three virulence factors were associated with a significantly lower risk of second UTI: cytotoxic necrotizing factor (relative risk [RR] = 0.0; 95% confidence interval [CI], 0.0, 0.42); hemolysin (RR, 0.10; 95% CI, 0.01, 0.69), and S fimbrial adhesin (RR, 0.25; 95% CI, 0.06, 1.00). Dr binding was associated with a 2-fold increased risk of second UTI (RR, 2.30; 95% CI, 1.23, 4.29). Half of all paired first and second UTI isolates from the same subject were apparently the same.