Many people are familiar with the infections that are commonly transmitted by sexual contact, usually referred to as sexually transmitted infections (STIs) or sexually transmitted diseases (STDs). Most know that STIs can be caused by bacteria, (such as gonorrhea, chlamydia, syphilis), viruses (such as herpes, HIV, hepatitis B), or protozoa (trichomonas). Fewer are familiar with another common bacterial STI – Mycoplasma genitalium, referred to here as Mg. Although Mg is a bacterium, it is difficult to grow in the laboratory, so diagnostic testing has been difficult to develop. DNA-based testing for STI diagnosis has made it easier to identify Mg infections, but these tests are still seldom performed and there is currently only one FDA-approved test for Mg infections that became available in early 2018.
Clinical conditions associated with Mg infections include urethritis (usually associated with discharge from the penis and pain with urination) and epididymitis (swelling and pain in one testicle) in men. Infection in women can cause cervicitis (inflammation of the cervix often associated with abnormal discharge or bleeding) and pelvic inflammatory disease (inflammation of the fallopian tubes associated with severe lower abdominal pain). These are also symptoms of gonorrhea and chlamydia. As with most STIs, these infections can occur together, and with overlapping symptoms, can complicate sorting out the cause. However, recent studies have shown Mg can be as common as chlamydia.
In the past, treatment for chlamydia was often effective against Mg, causing Mg diagnosis to be less important in treatment decisions. Now, new Mg strains have been identified, causing the commonly used antibiotics for chlamydia, such as azithromycin, to be less effective against these new strains.
As with the other bacterial STIs, some can be infected with Mg, not have symptoms, and still pass the infection on to a sexual partner, who then may develop symptoms. There is currently no recommendation for testing people without symptoms for Mg and testing is not widely available. Stay tuned for more information on this important STI that is likely to come out in the next few years.