Association between polycystic ovary syndrome and the vaginal microbiome: A case-control study

Background Polycystic ovary syndrome (PCOS) is the most common endocrinopathy in women of reproductive age. Some evidence suggests that dysbiosis of the gut microbiota could be associated with PCOS clinical parameters, but little is known for the association between vaginal microbiome and PCOS. Objective To determine differences in the vaginal microbiome between women with PCOS and healthy control women. Research design and methods In this case-control study, the women with newly diagnosed PCOS (n = 39) and healthy controls (n = 40) were included from the hospital and maternal and child health centre, respectively. The vaginal swabs were collected, and microbiome structures were identified by 16S rRNA gene sequencing. The screening values for potential bacteria biomarker for PCOS were assessed by receiver operating characteristic (ROC) curve method. Results There was significant difference in vaginal bacterial structures between PCOS and healthy control women. The vaginal bacterial species in the PCOS group were more diverse than the control group (Simpson index for PCOS group vs. control group: median 0.49 vs. 0.80, P = .008; Shannon index: median 1.07 vs. 0.44, P = .003; Chao1 index: median 85.12 vs. 66.13, P < .001). The relative abundance of Lactobacillus crispatus in the PCOS group was significantly lower than controls (P = .001), and the relative abundance of Mycoplasma and Prevotella was higher than controls (P < .001, P = .002, respectively). The Mycoplasma genus could be a potential biomarker for PCOS screening, as ROC analysis showed that the area under the curve (AUC) for the relative abundance of Mycoplasma was 0.958 (95% CI: 0.901-0.999). Subgroup analyses also showed these associations would not change among the women with the same BMI level and vagina cleanliness grading. Conclusions In the vaginal microbiome, the Mycoplasma genus was associated with PCOS. Further research is required to explore causal correlations between PCOS and the vaginal microbiome.