Mycoplasma genitalium, often called Mgen, is a sexually transmitted bacterial infection that can affect the urethra, cervix and rectum. Many infections cause no symptoms. When symptoms persist or return after treatment for another STI, Mgen may be considered.
Symptoms
Possible symptoms include burning or pain when urinating, genital discharge, bleeding after sex or between periods, and pelvic discomfort. Similar symptoms can occur with Chlamydia, Gonorrhea and other infections, so testing is important.
Testing
Mgen is diagnosed with a nucleic acid amplification test, using an appropriate urine or swab sample. Routine screening of people without symptoms is not generally recommended. Testing is particularly relevant for recurrent or persistent urethritis or cervicitis and may be considered in pelvic inflammatory disease.
Treatment and antibiotic resistance
Mgen can be cured with appropriate antibiotics, but antibiotic resistance is an important concern. Treatment should be prescribed by a healthcare professional and, where available, resistance testing can help guide antibiotic choice.
Penicillin and related beta-lactam antibiotics do not work because Mycoplasma bacteria have no cell wall. A single one-gram dose of azithromycin should not be used as stand-alone treatment because of high macrolide resistance and the risk of selecting further resistance.
Current CDC guidance recommends a two-stage treatment approach, ideally guided by resistance results. The exact regimen depends on test results, resistance patterns, pregnancy, other medicines and individual medical circumstances. Complete the prescribed course and return for reassessment if symptoms continue.
Partners and prevention
Sex partners of people with symptomatic Mgen may be offered testing and treatment when appropriate. Follow the treating service’s advice about avoiding sexual contact until treatment requirements have been completed. Condoms reduce the risk of sexually transmitted infections.
Possible complications
In women, Mgen is associated with cervicitis and pelvic inflammatory disease. Research has also found associations with some reproductive complications, although evidence for several long-term outcomes remains incomplete.
When to seek medical care
Arrange sexual health assessment for persistent genital discharge, burning when urinating, bleeding after sex, pelvic pain, recurrent urethritis or cervicitis, or if a partner has been diagnosed with Mgen.
Seek urgent medical assessment for severe pelvic or abdominal pain, fever with worsening illness, fainting, pregnancy with significant pain or bleeding, or sudden severe testicular pain.
Related topics
Sources and Further Reading
Last reviewed: 4 September 2026