By CATIE — Canada's source for HIV and hepatitis C information
"The bacterium Mycoplasma genitalium (MG) is sexually transmitted and can cause inflammation of the urinary and genital tracts in men and women. This germ may also be linked to other problems, including some cases of arthritis and, in women, pelvic inflammatory disease and infertility.
MG appears to be spread by unprotected anal or vaginal intercourse, as it can be detected in fluid samples from the penis, rectum and vagina. So far it has not been detected in fluid samples from the throat.
MG, like other sexually transmitted infections (STIs), can cause inflammation of delicate genital tissue. Such inflammation can make the genitals more susceptible to infection with other STIs, including HIV.
In high-income countries, overall rates of MG infection appear to be low, ranging between 1% and 3%. Several studies have found that rates of MG infection tend to be greater among people who seek care for STIs.
Urethritis is an inflammation of the tube (urethra) that carries urine out of the body. Common causes of urethritis are chlamydia and gonorrhea. However, testing of urine and other samples can fail to detect possible causes of urethritis. In such cases, and depending on the degree of distress caused by symptoms, some doctors may treat their patients with a presumed diagnosis of urethritis caused by MG and/or other STIs. In women, MG can cause inflammation of the urethra and cervix (cervicitis) and likely the uterus and the fallopian tubes.
Symptoms of urethritis in men can include one or more of the following:
Symptoms of cervicitis and urethritis in women can include one or more of the following:
MG is difficult to grow on a culture in the laboratory, meaning that many patients with an MG infection will have false-negative results for their culture. Some labs may have access to specialized tests that can multiply and then detect the genetic material or DNA of MG. Such tests are called nucleic acid amplification tests (NAAT).
Regimens for the treatment of MG can vary depending on the region or medical centre and the severity of the disease. In clinical trials comparing the antibiotics azithromycin and doxycycline, azithromycin resulted in more cures. However, those trials were done several years ago and since then MG may have acquired more tolerance and even resistance to azithromycin. Based on reports and clinical trials, there are at least two possible regimens of azithromycin that doctors can consider, as follows:
Unfortunately, these two regimens have not been compared against each other in clinical trials so doctors are not certain if one is better than the other.
There is also a 2 gram extended-release formulation of azithromycin (sold as Zmax SR by Pfizer). However, no data on the effectiveness of this dose on MG has been reported.
Increasingly, there have been reports of treatment failure when a single 1 gram dose of azithromycin is used in MG infection. In such cases, some STI experts suggest the use of another antibiotic, moxifloxacin (Avelox), given as 400 mg once daily for between seven to 10 days.
However, it is important to note that reports of MG resistant to both azithromycin and moxifloxacin have been documented.
We thank Marc Steben MD, Institut national de santé publique du Québec, for his helpful discussion, research assistance and expert review."