The following is a summary of “Is lactobacillus phage involved in the pathogenesis of bacterial vaginosis?,” published in the FEBRUARY 2023 issue of Obstetrics and Gynecology by Elnaggar J, et al.

For a study, researchers sought to investigate the role of Lactobacillus phages in the etiology of bacterial vaginosis (BV), the most common cause of vaginal discharge.

The study involved enrolling African American women who have sex with women with normal baseline vaginal microbiota and following them for 90 days using daily self-collected vaginal specimens to detect incident BV (iBV) (defined as Nugent score 7-10 on at least 2 consecutive days). Vaginal specimens on the first day of iBV (Day 0), along with every other day for the 10 days prior (Day -2 to -10), were selected for shotgun metagenomic sequencing (SMS) using an Illumina HiSeq 4000. 

Sequencing reads were processed using Kraken2 to determine taxonomic composition. Following assembly with the Megahit, contigs were analyzed using VIBRANT to investigate Lactobacillus phage origin and activity.

A total of 6 vaginal specimens from 4 participants who developed incident BV were sequenced (n=24). Normalized estimated reads originating from the Lactobacillus genus declined over time before incident BV while reads originating from Gardnerella vaginalis, Prevotella bivia, and Atopobium vaginae increased sharply on the day of incident BV. In addition, before incident BV, lytic Lactobacillus phages were found in 4/4 (100%) participants and correlated with decreased protective Lactobacillus spp.

The findings suggested that an interplay between Lactobacillus phages and protective Lactobacillus spp. may occur before BV’s onset. However, due to the small sample size, further research is needed to determine the role of Lactobacillus phages in BV pathogenesis.

Reference: https://www.ajog.org/article/S0002-9378(22)01012-2/fulltext