Mycoplasma hominis is a common mollicute bacteria, present in almost all humans in the urinary tract. However, it can sometimes cause infection which can be transmitted sexually. It is different from other STIs, in that monogamous couples can suddenly experience mycoplasma hominis even after years of exclusivity. The symptoms of a Mycoplasma hominis infection are similar to many other STIs and the condition can often be mistaken for gonorrhoea or chlamydia. You can also have mycoplasma hominis and not experience any symptoms at all.

Mycoplasma hominis affects up to 50% of sexually active males and females. The bacterium is present in almost everyone’s urinary tract in small quantities. Higher quantities cause the infection which can be transmitted sexually.

The bacteria present in (almost) everyone’s urinary tract in small quantities. However, in higher quantities it can cause infection which can be transmitted sexually. People with suppressed immune systems, such as those with HIV/AIDS or who have recently undergone an organ transplant, are more likely to contract this STI.

• Unprotected vaginal sex
• Sharing sex toys
• From an infected mother to her child during birth

Mycoplasma hominis infection can cause urethritis and increases the risk of vaginitis and pelvic inflammatory disease (PID) in women. It is particularly harmful for people who are immunocompromised, e.g. those with HIV/AIDS or those on immunosuppressant drug therapy.

Mycoplasma hominis can also increase the risk of contracting HIV infection if having sexual intercourse with an infected person, and may promote a shorter time period before the development of AIDS symptoms.