Characterization of the vaginal microbiota in Italian women with endometriosis: preliminary study

Abstract

Purpose: This cross-sectional study aims to assess the interplay between the vaginal microbiota and endometriosis.

Methods: 123 consecutive Italian fertile women, aged between 20 and 40 years old, were enrolled during a routine gynecological consultation; 24 were diagnosed with endometriosis and 99 did not complain of any gynecological disease. All women underwent a vaginal swab for the evaluation of the composition and diversity of vaginal microbiota by means of 16 s rDNA metagenomic sequencing.

Results: Compared to women with no gynecological disease, the vaginal microbiota in women with endometriosis showed a similar abundance of Lactobacillus spp.; however, a statistically significant lower abundance in the genera Pseudomonas (p < 0.01), Bifidobacterium (p < 0.05), Novispirillum (p < 0.0000001) and Sphingomonas (p < 0.0000001), and a statistically significant increase in the abundance of the genera Escherichia (p < 0.00001), Megasphaera (p < 0.00001), and Sneathia (p < 0.0001) were observed.

Conclusions: There is a complex interplay between vaginal microbiota composition and endometriosis, showing a distinct microbial signature in the bacterial genera usually found in dysbiosis.

Keywords: Dysbiosis; Endometriosis; Metagenomic analysis; Vaginal microbiota.

Fig. 1

Comparison of the alpha- and beta-diversity of the vaginal microbiota in relation to the presence of endometriosis. Faith’s phylogenetic diversity (A) and Shannon’s diversity index (B) were used to measure alpha-diversity within groups. The circles out of range represent the outliers. Principal coordinate analysis (PCoA) plots, and boxplot representations of within-group distances, of unweighted (C) and weighted (D) UniFrac distance matrices, are illustrated. Each dot represents the vaginal bacterial community composition of one individual. Groups were compared using Adonis for beta-diversity. F. Samples were rarefied to the smallest observed number of reads (3714). Group A, all women with endometriosis; group B, women with no gynecological disease

Fig. 2

Linear discriminant analysis with effect size measurement (LEfSe) of the vaginal microbiota in relation to the presence of endometriosis (A), and in relation to the hormonal therapy (B). On the left, histograms of the LDA scores were computed for statistically significant differentially abundant taxonomic units between the groups. On the right, cladograms highlight the relationships of the significantly different taxonomic units between the groups. Differences are represented in the color of the most abundant class, and each circle’s diameter is proportional to the taxon’s abundance. Group A, all women with endometriosis; Group B, women with no gynecological condition; group A1, women with endometriosis taking dienogest; Group A2, women with endometriosis and no hormonal therapy

Fig. 3

ANCOM test of the vaginal microbiota between endometriosis patients and women with no gynecological disease. W statistics represent the number of times the null hypothesis is rejected for a given taxon. Group A, all women with endometriosis; group B, women without gynecological diseases

Fig. 4

ANCOM test of the vaginal microbiota amongst women with endometriosis in relation to the hormonal therapy, and women without any gynecological disease. W statistics represent the number of times the null hypothesis is rejected for a given taxon. Group A1, women with endometriosis taking dienogest; group A2, women with endometriosis and no hormonal therapy; group B, women with no gynecological disease