Abstract: Objective: The purpose of this study was to investigate the microbiome differences in endometriosis (EMs) patients with infertility and to identify the relevant differential bacteria and microbiological biomarkers. Methods: This study was conducted in Chinese Academy of Medical Science Peking Union Medical College Hospital form April 2018 to September 2019, 66 patients with EMs were selected and their final diagnose were obtained by surgical report. They were divided into infertility group (n=17) and control group (n=49). Vaginal posterior fornix was the sampling site. After bacterial 16S-rRNA sequencing and bioinformatics analysis, bacteria community diversity algorithm (alpha, beta), PCoA distance matrix algorithm (Bray-Curtis and Unifrac matrix) and biological identification algorithm (LeFSe) were used to analyze the compositional difference of bacteria. Results: There was no significant difference in alpha diversity in the bacterial community between the two groups, while the content of Lactobacillus in the infertile group was slightly decreased in beta diverisity. Three kinds of bacteria showed significant statistical differences, Prevotella, Megasphere and Dialister, which were significantly increased in infertile patients. PCoA showed no significant difference. Proteobacteria at the phylum level and Gammaproteobacteria at the class level are underlying biomarkers. Conclusions: This study revealed that in EMs patients, whether infertility is associated with differences in the bacterial community in the lower reproductive tract, and changes in bacterial abundance may be used to assess differences in host immunity and symptoms in EMs infertility patients. It also played an important role in the study of mechanisms of EMs and the development of microbial diagnostics.

Key words: Endometriosis；, Microbiome；, Infertility, female；, 16S-rRNA sequencing；, Bioinformatics analysis