VIBRANT: A phase 1 randomized trial of multi-strain vaginal L. crispatus live biotherapeutic products in people with bacterial vaginosis.

Bacterial vaginosis (BV) is characterized by high microbial diversity. High recurrence rates following antibiotics may stem from poor recolonization by protective Lactobacillus species. This phase 1 randomized trial in the United States and South Africa evaluated two vaginally delivered live biotherapeutic products (LBPs) containing multiple Lactobacillus crispatus strains. After metronidazole treatment for BV, participants received either a placebo or 3 or 7 days of active LBPs. LBP strains were detected by metagenomics in 66.1% (47/71) of participants in the active arms in the first 5 weeks. Among those, nearly half (49%, 23/47) remained colonized at 12 weeks despite the short initial treatment course. Participants were most often colonized by one of three component strains, with no geographic differences in strain colonization observed. LBPs were safe, acceptable, and well tolerated, with no serious adverse events (AEs) reported. These results provide a foundation for the development of transformational interventions aimed at optimizing the vaginal microbiome.