Systematic review of co-culture methods for studying vaginal biofilm formation in bacterial vaginosis

Bacterial vaginosis (BV) is characterized by depletion of Lactobacillus spp. and increased abundance of facultative and strict anaerobic species. Gardnerella spp. initiates biofilm formation associated with BV pathogenesis. Vaginal biofilms act as virulence factors and reduce the effectiveness of antibiotic treatment for BV.

To systematically review the most commonly used methodologies for studying bacterial biofilms in bacterial vaginosis (BV), and to discuss how standardization can improve future studies.

A search was conducted in PubMed, Virtual Health Library (VHL), and Embase databases for articles addressing BV biofilms in vaginal dysbiosis, resulting in 66 included studies. Non-original studies, those involving bacteria unrelated to the vaginal environment, fungal species, and studies whose methods did not include bacterial biofilm models were excluded. The risk of bias in the selected articles was assessed using the RobDEMAT tool for in vitro studies and the RoB2 tool for in vivo studies.

The most commonly used method for biofilm experiments was the co-culture of Gardnerella vaginalis and Lactobacillus spp. Molecular-based studies consistently demonstrate the polymicrobial nature of vaginal biofilms, reinforcing the importance of utilizing co-culture assays with multiple bacterial species related to BV.

Standardizing bacterial co-culture models will allow that data from future studies to be reproducible and comparable. This will optimize time and resources in the search for novel treatments for BV, including testing for prebiotic and probiotic candidates.