Mycoplasma genitalium, also called M genitalium or Mgen, is a sexually transmitted infection that is caused by a type of bacteria. It’s transmitted through sexual contact.

According to the Centers for Disease Control and Prevention (CDC), in people with a penis, Mgen causes as many as 40% of persistent or recurrent infections of the urethra, the tube that carries urine and semen out of the body. In people with vaginas, having Mgen doubles the risk of infections of the genital tract, preterm delivery, infertility, and more.

Read on to find out more about what causes Mycoplasma genitalium, what it may look like, and what to do about it.

Mycoplasma genitaliumis a very small prokaryotic organism (bacteria) that when transferred from person to person through genital contact can lead to an infection usually in the urethra or genital tract.

Although people with Mgen often have few to no symptoms, it can cause symptoms similar to other sexually transmitted infections like chlamydia and gonorrhea, such as inflammation of the urethra and genital tract. If left untreated, it can lead to more serious problems such as vaginal bleeding, scrotum swelling, and even infertility in women.

Mycoplasma genitalium is classified as a “fastidious” bacteria, meaning that it grows slowly and requires hyper-specific conditions to thrive in a lab setting. This makes it difficult to study and means we still have a lot to learn about it.

Mycoplasma genitalium is described as a “stealth” pathogen, so most people don’t show any visible symptoms. In fact, a recent study in Britain showed that 94.4% of men and 56.2% of women with Mgen don’t develop any symptoms at all and are cleared of infection without any treatment.

If you do develop symptoms, they are similar to other STIs such as chlamydia or gonorrhea, which can sometimes lead to an incorrect diagnosis and delayed treatment.

For people with penises, Mgen most commonly leads to a condition called urethritis, an infection of the urethra or urinary tract. About 15-25% of cases of urethritis in the United States are associated with Mgen. Symptoms include:

For people with vaginas, Mgen can most commonly lead to conditions including:

Symptoms of these conditions include:

If you’re experiencing any of these symptoms, talk with a healthcare professional.

Mycoplasma genitalium is a bacteria that can cause a sexually transmitted infection. You can contract the infection through vaginal and anal sex, or any genital-to-genital contact. Some studies have suggested that Mycoplasma genitalium is just as easily transmissible as chlamydia.

Oral to genital contact has not yet been shown to lead to an infection. Studies are looking into whether there is potential for transmission of Mycoplasma genitalium from mother to child during pregnancy or delivery.

The diagnosis of Mycoplasma genitalium is difficult as there is no commercially available test. You may receive a diagnosis of Mycoplasma genitalium after failing treatment for a more common STI such as gonorrhea or chlamydia, or if you have symptoms but test negative for other STIs.

You may also receive a diagnosis of Mycoplasma genitalium if you are experiencing persistent urethritis or cervicitis symptoms.

To confirm the diagnosis,your doctor may order a nucleic-acid amplification test (NAAT), which can detect the specific genetic materials that make up a virus like Mycoplasma genitalium. This test will be conducted either through a urine sample, or a swab of the vagina or urethra.

Many commonly prescribed antibiotics may not be effective to treat the condition.

Antibiotic resistance

Recent studies have shown that Mycoplasma genitalium is becoming resistant to antibiotics like moxifloxacin, azithromycin, and macrolide, the first-line medications that are commonly used to treat it. This could be leading to stronger, more resistant strains that may be harder to treat.

Because Mycoplasma genitalium is resistant to many antibiotics, the CDC recommends the following treatment options:

If resistance testing is available:

  • If macrolide-sensitive:Doxycycline 100 milligrams (mg) orally 2 times/day for 7 days, followed by azithromycin 1 gram (g) orally initial dose, followed by 500 mg orally once daily for 3 additional days (2.5 g total)
  • If macrolide-resistant: Doxycycline100 mg orally 2 times/day for 7 days followed by moxifloxacin 400 mg orally once daily for 7 days

If resistance testing is not available:

  • If Mycoplasma genitaliumis detected by an FDA-cleared NAAT: Doxycycline 100 mg orally 2 times/day for 7 days, followed by moxifloxacin 400 mg orally once daily for 7 days

Any sexual partners you have should also be tested for Mgen, even if they are not experiencing symptoms.

As with many STIs, there are a few risk factors that may put you at a higher risk for contracting Mgen including:

  • having sex without a condom or other barrier method
  • a recent diagnosis of chlamydia or gonorrhea
  • multiple sexual partners (more than two) in the past 12 months
  • if you are a person living with HIV or AIDS

Yes, if you are pregnant and contract Mycoplasma genitalium there are a few serious complications that you should be aware of, including a higher risk for:

If you are pregnant and think you may have contracted Mgen, you should speak with a health professional or doctor right away as treatment can help prevent these complications.

For the many people who are asymptomatic, Mycoplasma genitalium will likely clear up without any temporary or long-lasting complications. There is a debate on whether this means that wide, population-based screening for Mgen is not needed.

In some cases, you may experience a persistent infection. According to a 2019 review, about 9% of people experience an infection lasting longer than 7 months.

If left untreated, women and people with female reproductive organs could potentially have issues with infertility due to the chronic inflammation, swelling, and scarring of the fallopian tubes that may occur from PID. This connection is still being studied

More studies need to be completed to fully understand the long-term consequences of untreated Mgen.

Is Mycoplasma genitalium a new STI?

Mycoplasma genitalium was first discovered to be an STI in the 1980s but the CDC didn’t officially declare it an STI until 2015. So although it has been around for over 40 years, it is getting attention now due to its high prevalence and its development of antibiotic resistance.

Can I have both Mycoplasma genitalium and gonorrhea/chlamydia at the same time?

Yes, you are at increased risk of becoming infected with Mycoplasma genitalium if you already have a different STI and may need a more complex treatment regimen.

If I don’t have symptoms but I get a diagnosis of Mycoplasma genitalium, do I still need to tell my partner(s)?

Yes! Contact notification is very important to the management of this and any STI. Your partner is usually treated the same way that you are. You should also contact partners from within the last 3 months and let them know they can get tested and treated.

Can you kiss someone with Mycoplasma genitalium?

Yes! Mgen is only transferred through direct genital to genital contact. It cannot be caught by kissing, hugging, using shared swimming pools or baths, or from toilet seats.

Mycoplasma genitalium is a relatively new, emerging bacteria that causes a sexually transmitted infection (STI). Oftentimes, infected individuals are asymptomatic and the bacteria is cleared naturally by the body. However, in symptomatic individuals, untreated infections have the potential to lead to serious conditions such as urethritis, cervicitis, PID, and potentially, infertility.

This infection is treated with antibiotics but recently certain strains of Mycoplasma genitalium have been forming a resistance to antibiotics. This has forced healthcare professionals to change antibiotic treatment regimens to combat this infection. Studies around this are ongoing.

As with any STI, it is important to use a condom or another protective barrier during sex to decrease the risk of infection.