Objective: Hydrogen peroxide producing lactobacilli are isolated from the vaginas of a majority of healthy reproductive age women. Their toxic and inhibitory effect against the overgrowth of pathogens in the vagina is documented by in vitro studies. Clinical studies concerning the role of hydrogen peroxide producing lactobacilli in vaginal infections are controversial.
Study design: The aim of this study was to isolate lactobacilli from women with major vaginal infections: bacterial vaginosis (BV), vulvovaginal candidiasis (VVC) and trichomoniasis (TV), and from women with normal flora (NF), to test their ability to produce hydrogen peroxide, to quantitate lactobacilli and to evaluate factors related to the colonization of vagina with hydrogen peroxide producing lactobacilli. The study group comprised 108 women: 27 with VVC, 26 with BV, 20 with TV and 35 with NF. Data was analysed with Fisher exact test, chi2-test, and ANOVA.
Results: Lactobacilli were isolated from 81.5% of women with VVC, 58% of women with BV (p=0019), 55% of women with TV (p=0.015) and from 86% of women with NF. The majority of isolates of lactobacilli from women with VVC, TV and NF produced hydrogen peroxide (77%, 63.5% and 80%, respectively), compared with women with BV where only 26.5% of isolates produced hydrogen peroxide (p=0.01). Quantitative analysis showed that in an overwhelming majority of women colonized with lactobacilli, their count was >10(7) CFU/ml. Upon evaluation of behavioural and demographic characteristics, we found that smokers had a lower incidence of isolation of hydrogen peroxide producing lactobacilli (p=0.018). Our results showed that women with BV lack lactobacilli, especially hydrogen peroxide producing ones. Women with TV had a lower rate of lactobacilli. In women with VVC, there was neither significant difference in the isolation of lactobacilli, nor in their ability to produce hydrogen peroxide, compared to women with NF.
Conclusion: Our results point out that hydrogen peroxide producing lactobacilli could protect against the development of BV, but not against VVC and TV.