Improved cure of bacterial vaginosis with single dose of tinidazole (2g), Lactobacillus rhamnosus GR-1, and Lactobacillus reuteri RC-14 Original paper

What Was Studied?

This randomized, double-blind, placebo-controlled clinical trial investigated whether the combination of a single 2g dose of tinidazole and daily oral probiotics (Lactobacillus rhamnosus GR-1 and Lactobacillus reuteri RC-14) improved bacterial vaginosis (BV) cure rates in women, compared to tinidazole alone. BV, a condition characterized by dysbiosis in the vaginal microbiome and reduction of protective Lactobacillus species, has shown poor long-term response to antibiotic treatment alone. The study aimed to determine if probiotic supplementation could enhance the therapeutic efficacy of tinidazole by restoring a more favorable microbial balance.

Who Was Studied?

Sixty-four Brazilian women diagnosed with BV based on Amsel’s criteria and Nugent scoring participated in the study. The participants were randomly assigned to either a placebo group or a probiotic group, both of which received the same tinidazole dose. The probiotic group also received daily capsules containing L. rhamnosus GR-1 and L. reuteri RC-14 for four weeks. Women with other vaginal infections, recent antibiotic use, or immunosuppression were excluded. The trial assessed both subjective symptoms and microbiological cure at the end of the treatment period.

What Were the Most Important Findings?

At the end of the four-week treatment, the probiotic group exhibited a significantly higher cure rate compared to the placebo group as measured by Amsel’s criteria and Nugent score. Women in the probiotic group were assessed with “normal” vaginal microbiota based on Gram stain, compared to the placebo group. Importantly, the study also noted reduced BV-associated microbial morphotypes (Gram-variable rods, curved anaerobes) and a statistically significant improvement in key clinical indicators, including pH, discharge, and odor in the probiotic group. While both groups used tinidazole, the probiotics played a key role in enhancing microbiota restoration. Notably, the probiotic strains used in the study are known for producing biosurfactants, bacteriocins, and signaling molecules that can disrupt pathogenic biofilms, particularly those formed by Gardnerella vaginalis. This mechanism may explain their strong microbiome-modulating effect.

What Are the Greatest Implications of This Study?

This study provides robust clinical evidence supporting the adjunctive use of probiotics with antibiotics to treat BV and improve microbiota restoration. By demonstrating that oral administration of specific Lactobacillus strains significantly improves cure rates and promotes a return to healthy vaginal flora, the study bridges microbiome science with practical gynecological care. Clinicians managing recurrent or treatment-resistant BV can consider integrating targeted probiotic strains to reduce recurrence and enhance long-term remission. Additionally, the study underscores the need for strain-specific probiotic selection, given the inconsistent outcomes with nonspecific lactobacilli. The use of probiotics also holds promise in preserving drug efficacy and reducing the need for prolonged antibiotic exposure, which aligns with antimicrobial stewardship principles and microbiome health preservation.