Vaginal colonization with E. Coli and lactobacilli in women with and without recurrent UTI

Vaginal colonization with E. coli (VEC) precedes UTI, and women with recurrent UTI often demonstrate persistent VEC, but the pathogenic mechanisms underlying these alterations have not been elucidated. Since strains of lactobacilli (LB) that produce hydrogen peroxide (H₂O₂) inhibit the growth of E. coli, we hypothesized that absence of H₂O₂-producing lactobacilli (LB+) may predispose to VEC and acute cystitis. To examine the relationships between vaginal colonization with LB+, VEC, and history of recurrent UTI, we obtained vaginal miroitai cultures from 140 women, 65 with a history of three or more UTIs in the past 12 months (cases) and 75 women without such a history (controls). Both cases and controls were attendees at a university health center, and did not have active UTI symptoms or recent antibiotic exposure at the time of enrollment. Sexual activity, spermicide use, and VEC were significantly more prevalent in the case group (OR 8.3, 4.2, 4.6; p<.001, .003, <.001 respectively). Spermicide use was associated with a greater risk of VEC (OR 12.5, p<.0001) and absence of LB+ (OR 2.9, p=.04). Women without LB+ were more likely than women with LB+ to have VEC (OR 4.0, p=.001). After controlling for spermicide use, the associations between VEC and absence of LB+ (OR 6.5, p=.02) and between VEC and history of recurrent UTI (OR 5.1, p=.004) remained evident in the nonspermicide users. We conclude that absence of LB+ may play an important role in the pathogenesis of recurrent UTI by facilitating E. coli introital colonization.