Mycoplasma genitalium: Fighting a little known, often drug-resistant STD

There's still a good chance you've never heard of it. But an emerging bacterial threat, mycoplasma genitalium, that can be passed through sex is making some headlines across the pond as the British Association of Sexual Health and HIV recently drafted guidance aimed at better detecting and treating it.

Stateside, the Centers for Disease Control and Prevention has also been keeping an eye on M. genitalium, or Mgen. Some research has been done to get a better sense of how prevalent it may be – with estimates generally indicating 1 to 2 percent of people have Mgen. But precisely how common it is remains unclear. Though frequently people with Mgen don't have any symptoms, it's linked with painful inflammation in the urinary tract, or urethritis, for men and infection of the reproductive organs, or pelvic inflammatory disease, and inflammation of the cervix, or cervicitis, in women. In addition, there are other potential concerns – which still require further study – that it could affect pregnancy, increasing the risk for a spontaneous abortion or loss of the pregnancy, and be associated with pre-term birth and infertility. "It is associated with symptoms in some individuals, and while there is concern about the potential to cause serious reproductive issues, more evidence is needed," according to the CDC, as the understanding of the infection, its impact and how to treat it continues to evolve.

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"Mycoplasma genitalium is clearly an emerging disease and sexually transmitted infection that merits increased recognition from clinicians and public health officials," says Dr. Arlene Seña, an associate professor of medicine at the UNC Institute for Global Health & Infectious Diseases, and medical director for the Durham County Department of Public Health in North Carolina. And as Seña has found in research she led supported by the National Institutes of Health, it's many times more common in high-risk young women who come in for treatment at STD, family planning, OB-GYN and clinical research clinics. "Women who are between 15 to 25 years of age with other STI risk factors can have a prevalence of up to 20.5 percent," she notes. The study's findings were first published online in the journal Clinical Infectious Diseases in January. Mgen prevalence was higher for African-American women (at 22 percent) studied, compared with white women (16 percent), though the study didn't evaluate the reasons for this disparity, which has been found with other STDs such as gonorrhea and chlamydia.

What's more, when it is detected, Mgen frequently has been found resistant to antibiotic treatment. Lisa Manhart, a professor of epidemiology at the University of Washington in Seattle, who has been researching Mgen for two decades, says the drug that's typically used to treat it, azithromycin, "cures people 50 percent of the time or less." She notes that M. genitalium is more prevalent than the common STD gonorrhea, and has much higher rates of antibiotic resistance. "Anytime treatment efficacy drops below 95 percent for gonorrhea people get very, very concerned," she says. "M. genitalium is more than twice as common, and our treatment failure rates are 50 percent or more." In such cases, clinicians must try another medicine. "You would need a different antibiotic – a more specialized antibiotic called moxifloxacin," Manhart says.

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The latest research seems to suggest that Mgen prevalence is increasing, too, she says. Though because it's flown under the radar, in regards to surveillance, and is often asymptomatic, it's not so easy to tell if that's the case. "The reason why we don't understand more about Mgen and how much it impacts sexually active men and women is due to the fact that we are limited by our detection methods," Seña says.

Still, for anyone who is symptomatic, including women who have persistent pelvic inflammatory disease or cervicitis and men with urethritis who don't respond to treatment, it's important to talk with a doctor about concerns. "In Europe [including] Scandinavian countries [and] Australia, they have more ready access to tests for M. genitalium," Manhart says. Whereas in the U.S., she says testing for Mgen has historically only been done in the context of research and at large academic medical centers. But "commercial laboratories have recently begun offering M. genitalium tests," Manhart adds. "So a physician can order a test through someone like Quest or LabCorp."

To control the spread of Mgen, experts say it's important that those who know they have it communicate that with sexual partners – even if it's uncomfortable. And, while more research is needed to understand what methods work best to control transmission, condom use – as with protecting against other STDs – is also encouraged.

[See: 6 Strategies for Breaking the Stigma of Living With an STD.]

Experts are hopeful, however, that with companies (namely, U.S.-based Hologic and the Australian firm SpeeDx, Manhart notes) seeking approval from the FDA for diagnostic Mgen testing, it will be possible in the future to better track – and treat – the potential threat.

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