You've Probably Never Heard of This STD. It Could Become the Next Superbug.

A man in consultation with a doctor. — (Image credit: Shutterstock)

Doctors in the United Kingdom are warning that a sexually transmitted infection called Mycoplasma genitalium could become a "superbug" if it's not identified and treated properly in patients.

But what exactly is this infection, and why are doctors worried about it?

Don't feel bad if you haven't heard of Mycoplasma genitalium — although the organism is well-known to infectious-disease specialists, the average doctor likely doesn't remember much about it after learning about it briefly in medical school, said Dr. William Schaffner, an infectious-disease specialist at Vanderbilt University Medical Center in Nashville, Tennessee. [Quiz: Test Your STD Smarts]

M. genitalium — which is sometimes called MG or MGen —is a bacterium that was first discovered in 1981, according to the British Association of Sexual Health and HIV (BASHH). It can cause sexually transmitted infections (STIs) in both men and women, Schaffner said. In men, the bacteria can cause inflammation of the urethra (called urethritis) that leads to symptoms such as a burning pain while urinating or discharge from the penis.

In women, the bacteria have been linked to inflammation of the cervix (called cervicitis), as well as symptoms such as bleeding after sex and painful urination. If left untreated, the bacteria may ascend through the cervix and lead to a condition called pelvic inflammatory disease (PID), Schaffner told Live Science. PID affects the female reproductive organs and can lead to pain in the lower abdomen, and in some cases, infertility, according to the Centers for Disease Control and Prevention.

Still, people who are infected with M. genitalium often have no symptoms, Schaffner said. It's estimated that about 1 to 2 percent of people in the general population have M. genitalium infection, according to BASHH.

Potential superbug?

Because symptoms of M. genitalium can resemble those of chlamydia, a more common STI, people with M. genitalium are often treated with antibiotics for chlamydia, according to CNN. But this treatment approach is a problem, because antibiotics for chlamydia don't work well for M. genitalium, and their use can promote antibiotic resistance.

"We are already seeing resistance to Mycoplasma genitalium because we are using antibiotics that treat chlamydia very well but [don't] treat mycoplasma very well," Dr. Mark Lawton, a consultant in sexual health and HIV and the clinical lead at the Liverpool Center for Sexual Health, told CNN.

That's why BASHH recently released guidelines that recommend testing for M. genitalium in patients with certain symptoms, such as urethritis or signs of PID.

The big problem with identifying and properly treating M. genitalium infections has been that "there has not been a simple, inexpensive diagnostic test available" for the condition, Schaffner said.

Now, several commercial tests are available in Europe, but they are not approved by the U.S. Food and Drug Administration (FDA), meaning they can't be used in the U.S., according to BASHH. Testing for M. genitalium is not widespread in the United States yet, Schaffner noted.

Indeed, a 2017 paper in the Journal of Infectious Diseases concluded that "the public health response to M. genitalium is in its infancy," and cited the lack of an FDA-approved test as a barrier to responding appropriately to the condition.

The availability of test for an infection is important because "when doctors are treating 'in the dark,' they don’t know what it is they're treating, and treatment isn't appropriate," Schaffner said.

A recent review concluded that more commercial tests are needed to both diagnose and guide treatment of M. genitalium; and that research is needed to understand the cost-effectiveness of routine testing for the infection.

Schaffner noted that 30 years ago, there was no test for chlamydia and doctors didn't treat the infection appropriately. But once a test became available, that changed; now the test is widely used, and the infection is effectively treated. "Once we had a test, doctors even learned how to spell chlamydia," Schaffner quipped.

Original article on Live Science.

Rachael is a Live Science contributor, and was a former channel editor and senior writer for Live Science between 2010 and 2022. She has a master's degree in journalism from New York University's Science, Health and Environmental Reporting Program. She also holds a B.S. in molecular biology and an M.S. in biology from the University of California, San Diego. Her work has appeared in Scienceline, The Washington Post and Scientific American.