No abstract

Lactobacillus rhamnosus DSM 14870 and Lactobacillus gasseri DSM 14869 were previously isolated from the vaginal epithelial cells (VEC) of healthy women and selected for the development of the vaginal EcoVag probiotic capsules. EcoVag was subsequently shown to provide long-term cure and reduce relapse of bacterial vaginosis (BV) as an adjunct to antibiotic therapy. To identify genes potentially involved in probiotic activity, we performed genome sequencing and characterization of the two strains. The complete genome analysis of both strains revealed the presence of genes encoding functions related to adhesion, exopolysaccharide (EPS) biosynthesis, antimicrobial activity, and CRISPR adaptive immunity but absence of antibiotic resistance genes. Interesting features of L. rhamnosus DSM 14870 genome include the presence of the spaCBA-srtC gene encoding spaCBA pili and interruption of the gene cluster encoding long galactose-rich EPS by integrases. Unique to L. gasseri DSM 14869 genome was the presence of a gene encoding a putative (1456 amino acid) new adhesin containing two rib/alpha-like repeats. L. rhamnosus DSM 14870 and L. gasseri DSM 14869 showed acidification of the culture medium (to pH 3.8) and a strong adhesion capability to the Caco-2 cell line and VEC. L. gasseri DSM 14869 could produce a thick (40nm) EPS layer and hydrogen peroxide. L. rhamnosus DSM 14870 was shown to produce SpaCBA pili and a 20nm EPS layer, and could inhibit the growth of Gardnerella vaginalis, a bacterium commonly associated with BV. The genome sequences provide a basis for further elucidation of the molecular basis for their probiotic functions.

Background To reduce acquisition and relapse of bacterial vaginosis (BV), lactobacilli must be maintained in the vaginal microbiome. Probiotic lactobacilli may aid this purpose. We investigated whether vaginal probiotics (containing Lactobacillus rhamnosus DSM 14870 and Lactobacillus gasseri DSM 14869) would result in vaginal colonisation with lactobacilli in women with and without BV. Methods This prospective, partially randomised, exploratory pilot study was conducted in Soweto, South Africa. Thirty-nine sexually-active, HIV negative women were enrolled from October 2014 to May 2016 into three arms. Women who did not have BV (Group 1, n = 13) self-administered probiotic capsules vaginally once daily for 30 days, then once a week until Day 190. Women diagnosed with BV were randomized into Group 2 (n = 12) or Group 3 (n = 14) and treated with the triple oral antibiotic combination for vaginal discharge syndrome per South African guidelines (cefixime 400 mg stat, doxycycline 100 mg BD for 7 days and metronidazole 2 g stat). Immediately after antibiotic treatment, women in Group 2 self-administered probiotic capsules vaginally once daily for 30 days then vaginally once a week until Day 190. Women in Group 3 were not given lactobacilli. Results During the study, L. rhamnosus DSM 14870 or L. gasseri DSM 14869, were isolated in 5/13 (38.5%) women in Group 1 compared to 10/12 (83.3%) women in Group 2 (p = 0.041). The 1-month and 6-month BV cure rates were similar (P >  0.05) between Group 2 (42 and 25%) compared to Group 3 (36 and 25%). In Group 2, no correlation was observed between the frequency of isolation of the two Lactobacillus strains and the 1-month or 6-month cure rate. Conclusions Supplementation with vaginal probiotic capsules resulted in colonisation of the vagina by the Lactobacillus strains (L. rhamnosus DSM 14870 and L. gasseri DSM 14869) contained in the capsules. We observed low initial cure rates of BV after a stat dose of metronidazole and that the probiotic did not improve BV cure rates or alleviate recurrence which could be due to treatment failure or very limited power of the study. Trial registration Registered at the Pan African Clinical Trial Registry (www.pactr.org) on April 13, 2018 (retrospectively registered). Trial identification number: PACTR201804003327269.