Mycoplasma genitalium is also known as MG or Mgen. It's a sexually transmitted bacterium that infects the urinary and genital tracts, or the rectum.

MG can cause non-specific urethritis (NSU) in men and pelvic inflammatory disease (PID) in women.

Symptoms of MG


The majority of people with MG have no symptoms and the infection will clear itself naturally in some cases. Others may have one or more symptoms.

Signs and symptoms in the penis:

  • pain when urinating
  • a discharge
  • pain in their testicles
  • proctitis, an inflammation in the rectum causing anal pain and discharge.

Signs and symptoms in the vagina:

  • vaginal discharge
  • pain in the lower abdomen
  • abnormal vaginal bleeding (intermenstrual bleeding)
  • bleeding after sex
  • PID has been linked to MG – PID can cause infertility and is also associated with pre-term births and spontaneous abortions.

Signs and symptoms in the anus: 

  • pain and discharge 
  • proctitis, an inflammation in the rectum causing anal pain and discharge. 

 Rectal MG infection is often asymptomatic, but not always. 

How MG is passed on


MG is spread through unprotected vaginal or anal sex. It's most prevalent among people who have multiple sexual partners.

You should use a condom while having sex to reduce the risk of getting it or passing it on.

Testing for MG


MG testing at the sexual health clinic isn't routine as with other STIs and you probably won't be tested for MG unless you have symptoms.

If you have symptoms, MG is diagnosed through by carrying out a simple urine test, or a swab from inside the vagina. Swabs from the rectum might be taken if you have rectal symptoms.

If a test shows you do have MG, then your current sexual partners should be tested too, even if they're not showing symptoms.

Everyone who's sexually active should get regular checkups at their local sexual health clinic. It's especially important for people who have multiple sexual partners or who struggle with condom use.



MG is treated with antibiotics.

Some strains have developed resistance to commonly used antibiotics. It may take several rounds of different drugs to clear the infection.

You may still be able to pass it on for up to 14 days after completion of treatment so avoid unprotected sex.

You will be asked to test again after treatment to make sure the infection has gone. 

Treatment of MG for people who have HIV is the same as for HIV-negative people.

Often MG will clear on its own and you will not be prescribed treatment.