Effects of Bacterial Vaginosis Associated Bacteria, Endogenous Lactobacillus and Sociodemographic Factors on Vaginal Colonization with the Probiotic Lactobacillus crispatus CTV-05: A Study of the Intervention Cohort in a Phase IІA Clinical Trial of LACTIN-V® in San Francisco, USA

Abstract

Several fastidious bacteria have been associated with bacterial vaginosis (BV), but their role in lactobacilli recolonization failure is unknown. This study examined the effect of seven BV-associated bacterial species and two Lactobacillus species on vaginal colonization with L. crispatus CTV-05 (LACTIN-V). Twenty four women with BV were treated with metronidazole vaginal gel and then randomized 3:1 to receive either LACTIN-V or placebo. Vaginal swabs for L. crispatus CTV-05 culture and 9-bacterium specific 16S rRNA gene quantitative PCR 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 the day 10 or the 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 104.5 to 104.3 16S rRNA gene copies per swab in women who colonized with CTV-05 but increased from 105.7 to 107.3 in those who failed to colonize (p=0.19). Similarly, the median concentration of Atopobium spp. reduced from 102.7 16S rRNA gene copies per swab to below limit of detection (375 rRNA gene copies per swab) in women who colonized with CTV-05 but increased from 102.7 to 106.6 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). These results suggest that vaginal concentration of certain BV-associated bacteria, vaginal intercourse during treatment and presence of endogenous L. crispatus at enrollment predict failure of colonization with probiotic lactobacilli.