Effects of bacterial vaginosis-associated bacteria and sexual intercourse on vaginal colonization with the probiotic Lactobacillus crispatus CTV-05
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Several fastidious bacteria have been associated with bacterial vaginosis (BV), but their role in lactobacilli recolonization failure is unknown. We studied the effect of 7 BV-associated bacterial species and 2 Lactobacillus species on vaginal colonization with Lactobacillus crispatus CTV-05 (LACTIN-V). Twenty-four women with BV were given a 5-day course of metronidazole vaginal gel and then randomized 3:1 to receive either LACTIN-V or placebo applied vaginally once daily for 5 initial consecutive days, followed by a weekly application over 2 weeks. Vaginal swabs for L. crispatus CTV-05 culture and 9 bacterium-specific 16S rRNA gene quantitative polymerase chain reaction assays were analyzed on several study visits for the 18 women receiving LACTIN-V. Vaginal colonization with CTV-05 was achieved in 61% of the participants receiving LACTIN-V at either day 10 or day 28 visit and 44% at day 28. Participants not colonized with CTV-05 had generally higher median concentrations of BV-associated bacteria compared to those who colonized. Between enrollment and day 28, the median concentration of Gardnerella vaginalis minimally reduced from 10 to 10 16S rRNA gene copies per swab in women who colonized with CTV-05 but increased from 10 to 10 in those who failed to colonize (P = 0.19). Similarly, the median concentration of Atopobium spp. reduced from 10 16S rRNA gene copies per swab to below limit of detection in women who colonized with CTV-05, but increased from 10 to 10 in those who failed to colonize (P = 0.04). The presence of endogenous L. crispatus at enrollment was found to be significantly associated with a reduced odds of colonization with CTV-05 on day 28 (P = 0.003), and vaginal intercourse during the study significantly impaired successful CTV-05 colonization (P = 0.018). Vaginal concentration of certain BV-associated bacteria, vaginal intercourse during treatment, and the presence of endogenous L. crispatus at enrollment predict colonization with probiotic lactobacilli.