Lactobacillus reuteri can  reduce Gardnerella induced bacterial vaginosis in mice and modulate immune markers

Abstract Background Healthy vaginal microbiome is dominated by Lactobacilli, which constitute a strong line of defense against vaginal diseases like Bacterial vaginosis (BV). Bacterial Vaginosis is a polymicrobial disease characterized by gradual replacement of predominant population of Lactobacillus with anaerobic uropathogens such as Gardnerella vaginalis (GV), Prevotella and Mobiluncus spp. Due to antibiotic resistance in these pathogens, Lactobacillus spp. have been given attention in the prophylaxis and prevention of infections such as, urinary tract infections, genital infections and BV. Current study describes role of L. reuteri in reducing BV in a GV induced BV murine model. In addition, immunomodulatory effects of L. reuteri were assessed by analyzing gene expression of inflammatory and anti-inflammatory markers by real time PCR in vaginal tissue.Methods Study was divided into two parts. In phase 1, two groups of mice were intravaginally administered with L. reuteri and GV at a dose of 1 x 10 6 CFUml -1 and 5 x 10 5 CFUml -1 respectively and their colonization was confirmed by re-isolation of these strains in vaginal washes. In phase 2, prophylactic efficacy of L. reuteri in GV induced BV mice model were observed by considering clinical scoring, re-isolation frequency, bacterial load, change in epithelium of vaginal tissue and tissue inflammatory and anti-inflammatory markers.Results A significant reduction in clinical scores and re-isolation frequency was noticed in GV challenged pre- L. reuteri colonized animals (prophylactic group). On 10 th day, L. reuteri restricted the growth of GV and kept its count significantly lower than in GV positive control group. Reduction in epithelial thickness and exfoliation was noticed in histological sections of treated group as compare to that in positive control group. In addition to their antimicrobial potential against GV, a depletion in IL-6, IL-1β and elevation in IFN-γ was noticed in L. reuteri treated GV challenged mice.Conclusions Based on aforementioned findings, it is concluded that L. reuteri could be considered a natural candidate for therapies of female genital infections.