Researchers at The Washington University School of Medicine, in the U.S. have found metronidazole, an antibiotic, can inhibit the growth of endometriosis in mice by regulating the mice’s gut microbiome. The finding opens up the potential of a new, cost-effective treatment for women with endometriosis.

“We used a cocktail of four different antibiotics, and later treated the micewith each individually, and found out that only the antibiotic metronidazole was able to suppress the growth of the endometriotic lesion [in the mouse],” says Ramakrishna Kommagani, PhD, an assistant professor of obstetrics and gynecology at Washington University’s Center for Reproductive Health Sciences. Kommagani is the lead author of the study published in the journal Human Reproduction.

Endometriosis is a recurrent and progressive condition that occurs when the lining of the uterus, the endometrium, grows outside the uterus on other organs such as ovaries, the Fallopian tubes; in severe cases, these tissue lesions can cause organs to fuse together. It affects 176 million women globally — about 25 million women in India alone, according to the Endometriosis Society of India — and is one of the top three causes of infertility among women. There is no cure for the condition at present. Only the symptoms of endometriosis – primarily pain and irregular menstruation – can be treated.

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“At present, the treatment [for endometriosis] is to stop menstruation using hormonal pills, injections or IUDs,” says Dr. Rishma Dhillion Pai, gynaecologist based in Mumbai and board member of World Endometriosis Society. Standard hormone treatments for endometriosis can cost up to Rs. 3,000 a month or more, over the course of a lifetime. For a person in a low-income bracket, the treatment is costly; for anyone, the treatment comes with a variety of side effects that range from breast tenderness, mood swings, headaches, nausea, cramps, bloating or weight gain, to an increased risk of blood clots and stroke. Advanced cases of endometriosis might require surgery, but even then, there is no guarantee the tissue lesions will not recur.

“Endo is an enigmatic disease. There is a huge amount of research worldwide; the cause is still unknown. This study could be an asset in the long term, but at the moment it is not mainstream or path-breaking,” says Dr. Pai. Indeed, scientists already knew of a connection between endometriosis and gut bacteria; previous studies have found young women and girls with increased susceptibility to inflammatory bowel disease are more likely to develop endometriosis. The newest study confirms the link, finding that levels of a specific, protective type of gut bacteria were very low in the mice with endometriosis. The authors say this suggests that, in the future, a probiotic treatment could be developed to regulate the condition, in addition to an antibiotic treatment.

Like any other incurable disease, a lot of research is being done on endometriosis worldwide to understand the various factors that might be contributing to this disease. But little is underway in India. Most domestic gynaecological and other allied societies like Indian Society for Assisted Reproduction (ISAR), Indian Association of Gynaecological Endoscopists (IAGE), Federation of Obstetricians & Gynaecologists of India (FOGSI) have dedicated endometriosis committees which focus on publications, newsletters and workshops focused on endometriosis management; none of them are seriously research-based, and all the members are clinicians, not research scholars, says Dr. Pai, who has held leadership positions within each of these organizations.

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“Research on this subject is very little, just like any other research in India. There is no major support or grants. Most of the research in this field stems from pharmaceutical companies,” she says. Government funding is more focused on saving maternal and child lives than on refining the understanding and management of chronic, painful, but not deadly, conditions like endometriosis, she adds.

The researchers behind the latest study say they will now test the effects of metronidazole in women with endometriosis through a large, multicentre clinical trial to test the drug. The success of the study could mean a more cost-effective way to treat the disease, but Dr. Pai, and other doctors interviewed, expect advances in endometriosis treatment to be much more incremental.

“So far none of the studies have radically changed how the disease is treated. We have to wait and see how this study develops,” she says.