# Regulatory Effects of Lactobacillus crispatus and Lactobacillus rhamnosus on the Formation and Composition of Gardnerella Biofilms

## TL;DR

This study explores how Lactobacillus crispatus and Lactobacillus rhamnosus inhibit Gardnerella biofilms, which are linked to bacterial vaginosis recurrence.

## Contribution

The study identifies hydrogen peroxide and D-lactic acid as key bioactive components in Lactobacillus anti-biofilm activity.

## Key findings

- Hydrogen peroxide and D-lactic acid are prominent in inhibiting Gardnerella biofilm formation.
- Inhibitory activity does not alter the composition of pre-formed biofilms.
- Lactobacillus species show potential for probiotic-based treatment of bacterial vaginosis.

## Abstract

Bacterial vaginosis (BV), the most common lower genital tract infection among women of childbearing age, is characterized by a decline in Lactobacillus populations and the excessive proliferation of anaerobic bacteria. Clinically, metronidazole remains the first-line therapeutic agent. However, the increasing recurrence rate has become an urgent clinical challenge. An important factor of BV recurrence is the persistent presence of Gardnerella biofilms, which enhances pathogenic resistance to antibiotics. In contrast, a healthy vaginal microbiome, predominated by Lactobacillus, exerts protective effects by producing antimicrobial compounds that inhibit BV pathogen colonization and restore microbial homeostasis. Given this, Lactobacillus preparations have gained widespread attention for their adjunctive therapeutic potential in BV management. Accordingly, in this study, we selected two extensively investigated Lactobacillus species, Lactobacillus crispatus and Lactobacillus rhamnosus, to evaluate their inhibitory capacity against Gardnerella biofilms. Our findings suggest that hydrogen peroxide and D-lactic acid are prominent bioactive components involved in the inhibition of Gardnerella biofilm formation by these Lactobacillus species, though the potential contribution of bacteriocins and other uncharacterized factors cannot be excluded. Notably, this inhibitory activity is not accompanied by alterations to the composition of pre-formed biofilms. This study clarifies the anti-biofilm mechanism of specific Lactobacillus, providing a valuable reference for future research on probiotic-based strategies for the treatment of BV.