Doctors are urging more research into a little-known sexually transmitted infection that may be more common than thought.
Scientists have known for decades about mycoplasma genitalium, or M. genitalium or M. gen., a sexually-transmitted infection that may cause genital pain, bleeding and swelling, and has been linked to infertility and miscarriage. However, it wasn't until 2019 that the first Food and Drug Administration-approved test for M. gen. became commercially available. Many cases may be going undiagnosed and untreated, doctors warn.
“It’s a real concern,” said Dr. Irene Stafford, associate professor of maternal-fetal medicine at McGovern Medical School at UTHealth Houston. “Why are we not looking into this?”
Stafford called for more research and testing for the bacterial infection Tuesday during the Centers for Disease Control and Prevention conference for prevention of sexually transmitted diseases, where CDC officials warned about an “out of control” rise in STDs.
Similar to chlamydia and gonorrhea, M. gen. is sometimes asymptomatic, but it may lead to severe complications in both men and women. In men it can cause urethritis, a swelling and irritation of the urethra. In women, M. gen. is associated with cervical swelling, pelvic inflammatory disease, miscarriage, preterm birth, and infertility. In May, a large study published in the journal Sexually Transmitted Infection found the risk of preterm birth increased nearly twofold among women with M. gen.
However, more research is needed to determine the longterm risks from M. gen infection, experts said.
What are symptoms?
Because testing is relatively new, doctors don't have to report diagnosed cases, and the CDC doesn't recommend routine screening, it’s not clear how prevalent the STI is or who is most at risk. A patient is typically screened for it only if symptoms persist after testing negative for other STIs.
“We learn more about the epidemiology of sexually transmitted infections when we have better testing methods, said Erik Munson, an assistant professor of medical laboratory science at Marquette University in Milwaukee.
Symptoms can include:
- Pain and discomfort while urinating.
- Abnormal discharge for both men and women.
- Women might also experience pain in the lower abdomen and bleeding after sex.
As many as 20% of sexually active women and 16.5% of men between the ages of 15 to 24 may be infected with M. gen., according to Lisa Manhart, a professor of epidemiology at the University of Washington School of Public Health.
In comparison, chlamydia, the most commonly reported STI in the U.S., ranges from 4% to 7% for sexually active young women, depending on location and risk factors.
Given its association with pregnancy complications, Stafford believes that high-risk pregnant women should be screened for M. gen. But screening programs can be expensive, especially without more research on risks available to justify the costs.
“We have really good studies showing if we screen and treat chlamydia and gonorrhea, we can actually prevent infertility and PID [pelvic inflammatory disease],” Manhart said “We don’t have that kind of evidence for M. genitalium.”
The calls for more research have an urgency — the bug has developed resistance to the most common antibiotic used to treat STIs, azithromycin, or the “Z-Pack,” according to the CDC.
Another antibiotic, moxifloxacin, is effective but can cause serious side effects, making it an especially risky choice for pregnant women. Plus, the more moxifloxacin exposure M. gen. has, the more likely it is to become resistant to that antibiotic, too, experts caution. Beyond moxifloxacin, there are very few treatments for the infection.
“M. genitalium has quickly developed resistance to every antibiotic that’s been used to treat it,” Manhart said. “We already have untreatable infections.”
While these instances are rare, some worry that M. gen is on its way to becoming a completely resistant superbug. Until scientists find new treatments for the STI, public health experts are approaching its treatment with caution.
For now, the CDC says the best strategy for treating M. gen involves testing for antibiotic resistance before deciding which drugs to use. Those tests aren’t FDA approved, however.
“The CDC is putting major stock in resistance testing, and right now it’s not readily available,” Munson said.
Only a few specialized research centers can test whether the infection is resistant to an antibiotic. While companies are working on widely available versions, they could be years away, as well as new or repurposed antibiotics effective against the stubborn bug, Munson said.
Experts hope more public awareness of the STI could give a much needed boost to research efforts.
“Because the implications of untreated M. gen. on fertility and sexual health is real,” Stafford said.