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 introitai 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 lactobaciili 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 lactobaciili may be important in the pathogenesis of recurrent UTI by facilitating E. coli introitai colonization.