Investigation of the female genital tract microbiome and its association with hydrosalpinx in women undergoing salpingectomy.

Objective: To describe the microbiome of the vagina and fallopian tubes (FT) and its relation with hydrosalpinx.

Methods: Case-control study was conducted in women who underwent salpingectomy for hydrosalpinx (case) or other indications (controls). Samples were obtained during surgery and subjected to 16S rRNA amplicon sequencing, and analyses of alpha diversity and beta diversity measures were compared between sites and groups. Differential abundance of bacteria associated with vaginal dysbiosis was compared between cases and controls.

Results: Nine women with hydrosalpinx and 23 women without hydrosalpinx were included in the study. The mean age of studied women was 41 (range: 29-54) and most (89%) were premenopausal. After in silico decontamination, only 30% of control FT samples and 10% of case FT samples had evidence of bacterial presence. The vaginal microbiome of control patients showed greater abundance of lactobacilli, whereas the vaginal microbiome of case patients contained relatively more bacterial vaginosis-associated bacteria, such as Prevotella and Atopobium. A significant difference was found in alpha and beta diversity between vaginal and FT microbiomes in control patients as FT samples were more diverse. We found that women with hydrosalpinx had a more "dysbiotic" vaginal microbiome and in women without hydrosalpinx, microbial composition within the vagina and FT differed, possibly representing two distinct ecological environments.

Conclusion: Women undergoing salpingectomy for various reasons harbored bacteria within their FT, while women with hydrosalpinx generally did not. This suggests that even though infection may be an underlying cause of hydrosalpinx, bacteria may not be present by the time patients require surgery.