Towards a microbiotic marker for endometriosis?
The oral, gut, and vaginal microbiota of women suffering from endometriosis display specific characteristics. These bacterial signatures may one day serve as biomarkers for diagnosing the disease and its severity.
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About this article
Endometriosis affects around 10% of women of childbearing age, with symptoms including dysmenorrhea, dysuria, pelvic pain, and reduced fertility or even infertility.
One diagnostic tool, laparoscopy, is invasive and delays treatment. Hence the hope of one day finding a non-invasive marker.
We may have to look no further, thanks to a study by Australian researchers who examined three microbiomes (oral, gut, and vaginal) to identify a bacterial signature of endometriosis.
Greater diversity in oral and gut microbiota
A total of 64 women were included in the study 1 :
- 24 with gynecological symptoms but laparoscopically confirmed no-endometriosis (N-ENDO)
- 21 with laparoscopically confirmed endometriosis (ENDO)
- and 19 controls with no known gynecological symptoms or infertility concerns (HC)
(sidenote: Alpha diversity Number of species coexisting in a given environment ) analyses revealed initial differences: the HC healthy controls had a more diverse oral and gut (but not vaginal) microbiota than the N-ENDO and ENDO groups.
10% Endometriosis affects roughly 10% (190 million) of reproductive age women and girls globally. ²
Bacteria that signal disease...
Above all, the vaginal flora of the ENDO group was richer in Escherichia, Enterococcus, and Tepidimonas.
Their stools contained more Lactobacillus, but also more Phascolarctobacterium, a bacterium known to be more abundant in the peritoneal fluid of these patients, raising the hypothesis of a possible bacterial translocation from the gut to the peritoneum.
Furthermore, Fusobacterium was more abundant in the oral cavity: could this opportunistic pathogen, implicated in periodontal disease, explain the higher incidence of gum inflammation in women suffering from endometriosis?
... and its severity
Microbiota also appear to signal the severity of endometriosis:
- stools show a greater abundance of Actinomyces in cases of minimal/mild endometriosis (stages 1 and 2) and of Paraprevotellaceae in cases of moderate/severe endometriosis (stages 3 and 4);
- the oral microbiota is enriched with Cardiobacterium in cases of minimal/mild endometriosis and with Fusobacterium in cases of moderate/severe endometriosis;
- the vaginal flora contains more Blautia, Dorea, Collinsella, and Eubacterium in moderate/severe endometriosis.
As is often the case, further work on larger cohorts is needed to confirm these findings.
However, the study offers hope for the future development of non-invasive screening for endometriosis and its severity... or perhaps even its treatment.
1. Hicks C, Leonardi M, Chua XY, Mari-Breedt L, Espada M, El-Omar EM, Condous G, El-Assaad F. Oral, Vaginal, and Stool Microbial Signatures in Patients With Endometriosis as Potential Diagnostic Non-Invasive Biomarkers: A Prospective Cohort Study. BJOG. 2025 Feb;132(3):326-336. doi: 10.1111/1471-0528.17979.
2. https://www.who.int/news-room/fact-sheets/detail/endometriosis
