The profiles of vaginal microbiota in postmenopausal women with atrophic vaginitis

Objective To identified the profiles of vaginal microbiota in postmenopausal women with or without atrophic vaginitis (AV), and investigate the potential correlations between vaginal bacterial composition and AV pathogenesis. Methods Thirty eligible patients, who were suffering with AV, were designated as AV group. In addition, a group of post-menopausal women remaining genital symptoms free were enrolled and designated as control group. The structure of bacteria communities present in the samples were identified by classifying 16S rRNA gene sequences in each sample using next-generation deep sequencing and bioinformatic analysis. To investigate differences of community composition between the two groups, a stepwise discriminant analysis was performed using the log-ratio-transformed proportions and canonical transformation for the species. In order to determine if a statistical relationship existed between species relative abundance and genital symptom score, the Spearman’s correlation coefficient analysis were used. Results A total of 60 vaginal samples were sequenced and the retrieved sequences were from 288 genera. The canonical variable transformed from total species proportions differed significantly between AV group and control group (P<0.05), while the relative abundance of 12 key vaginal genera were also significantly different between groups. Lactobacilli universally existed in most healthy post-menopausal women’s vaginal communities with a predominant abundance. The relative abundance of Gardnerella (41.7%) in AV women significantly increased compared with control group (16.7%) and played a dominant role in vaginal communities in place of Lactobacilli (53.2%, P<0.000 1). Meanwhile, the relative abundance of Lactobacilli in AV group significantly decreased from 53.2% to 11.2% (P<0.000 1), and lost its biological superiority. The results also indicated that among the most 5 key taxa present in all communities, Lactobacillus was negative correlated (r=-0.301, P<0.001) with symptom score, whereas Gardnerella (r=0.278, P<0.001) and Atopobium (r=0.166, P<0.05) was positively correlations with genital symptom. Conclusion The pathogenesis of atrophic vaginitis were closely related to disruption of vaginal commensal microbiota in postmenopausal women. After menopause, Lactobacillus in dominant proportion drove the main protective functions and maintaining the health of vagina. Along with Lactobacillus, we noted that two genera, Gardnerella and Atopobium, were detected to have association with genital symptom score. The overgrowth of these two genera might increase the risk of AV. Key words: Perimenopausal syndrome; Treatment effectiveness; Menopausal hormone therapy