There is a great bacterial diversity in the microbiota of the female reproductive system
The female reproductive system is not sterile: beyond the already known vaginal microbiota, researchers have described a great diversity of bacteria all throughout the reproductive organs.
Knowledge of the vaginal microbiota has improved in recent years because it is anatomically accessible. Chinese researchers have gone further by identifying the composition of the microbiota for each organ of the female reproductive tract, including the vagina, cervix and Fallopian tubes.
Samples were taken from 6 areas (vagina, posterior fornix, cervical canal, Fallopian tubes, endometrium, peritoneal fluid) from 110 female volunteers of childbearing age, and the bacterial population of each sample was described.
First observation: the various organs are not sterile and harbor an extremely diverse bacterial population throughout the tract. The vagina and uterus are dominated by Lactobacillus (L. crispatus, L. iners, and other Lactobacillus spp). In the endometrium, these bacteria progressively give way to Pseudomonas, Acinetobacter, Vagococcus, and Sphingobium, whose proportions increase as far as the Fallopian tubes.
Second observation: the bacteria observed in a single subject vary depending on the menstrual cycle and the presence, or not, of gynecological diseases (benign uterine tumors, adenomyosis, endometriosis-induced infertility). This study gives insights into the nature of the vaginal and uterine microbiota in the broad sense. It also revealed that analyzing the microbiota of the lower female reproductive tract may give an indication of diseases confined to the upper reproductive tract (fibroids, endometriosis, etc.). These results open the door for other studies on diseases in this anatomic region, including those occurring during pregnancy.
Chen C et al. The microbiota continuum along the female reproductive tract and its relation to uterine-related diseases. Nature Communications 8, Article number: 875 (2017).