Female upper reproductive tract harbors endogenous microbial profiles

Abstract

The vaginal milieu is known to have an active microbiome (>90% of Lactobacillus), but the microbial composition of the upper reproductive tract is not well established, especially in the Fallopian tubes. The first studies on the Fallopian tubes from women diagnosed with a benign disease or for prophylaxis suggest that this site supports an endogenous microbiome. However, today we lack the knowledge of the microbial composition in Fallopian tubes in the non-diseased conditions (as collecting samples from these sites may hamper the tissue and future fertility). Our study includes 24 fertile women with benign uterine pathology submitted to abdominal hysterectomy or tubal ligation at Hospital Universitario Virgen de Arrixaca Murcia, which endometrial and Fallopian tube samples were collected between January and July 2019. After DNA extraction, “Ion 16S Metagenomics Kit” (Ion S5™ System) was used to exploit the V5 to V9 regions of the 16S rRNA gene. Primary data analysis was performed with Torrent Suite™ Software v5.12.1 and advanced analysis using Ion Reporter™ software v5.18.0.2. In our study, distinct microbial community profiles in the Fallopian tubes confirm that this genital tract site harbors an endogenous microbiome and in big part is shared with the endometrial microbial profile (69% of the detected taxa). Nevertheless, 17 bacterial taxa were exclusively detected in the Fallopian tubes that included Enhydrobacter, Granulicatella, Haemophilus, Rhizobium, Alistipes y Paracoccus, among others, while 10 were found only in the endometrium, including Klebsiella, Olsenella, Oscillibacter and Veillonella (FDR <0.05). Regarding the endometrium samples, our study shows that method collection has an influence in results, where there is a Lactobacillus-dominance in fertile women with samples obtained transcervically while Acinetobacter, Arthrobacter, Coprococcus, Methylobacterium, Prevotella, Roseburia, Staphylococcus, Streptococcus were less abundant in patients which samples are collected by methods with lower vaginal and cervical contamination. Although upper reproductive tract is a low microbial biomass site, our results suggest that this upper reproductive site supports an endogenous microbiome that could be characteristic of each individual.