Inverse Association of H2O2-Producing Lactobacilli and Vaginal Escherichia coli Colonization in Women with Recurrent Urinary Tract Infections

Women with recurrent urinary tract infection (UTI) often demonstrate persistent vaginal colonization with Escherichia coli. Since strains of lactobacilli that produce hydrogen peroxide inhibit the growth of E. coli, the absence of these strains may predispose to E. coli colonization and to UTI. To test this hypothesis, vaginal introital cultures were obtained from 140 women, 65 with recurrent UTI (case-patients) and 75 without (controls). Vaginal E. coli colonization was significantly more frequent in case-patients than controls (35% vs. 11%; P < .001) and in women without H2O2-positive lactobacilli than in women with (odds ratio OR, 4.0; P = .01). Spermicide use was associated with greater risk of vaginal E. coli colonization (OR, 12.5; P < .001) and with absence of H2O2-positive lactobacilli (OR, 2.9; P = .04). The inverse association between H2O2-positive lactobacilli and vaginal E. coli colonization remained in case-patients after controlling for spermicide use (OR, 6.5; P = .02). Thus, absence of H2O2-positive lactobacilli may be important in the pathogenesis of recurrent UTI by facilitating E. coli introital colonization.