Mycoplasma genitalium

• A non-culturable bacteria that can cause sexually transmitted infection.
• Often carried asymptomatically, but can cause urethritis, cervicitis and possibly PID.
• Not well known, but likely more common than gonorrhoea, less common than chlamydia.
• The availability of testing varies between regions – check with your local laboratory.

Significance in many situations still not well understood.

• Asymptomatic anorectal colonisation is common in men who have sex with men (MSM).
• Uncertain whether causes proctitis or epididymo-orchitis in men.

Second line investigation in people where chlamydia and gonorrhoea have been excluded / already treated, and have:

• Recurrent or persistent urethritis that has not resolved with doxycycline treatment for non-gonococcal urethritis.
• Cervicitis or PID that has not responded to standard treatment.

Treatment can be complicated.

• Commonly resistant to first line treatment (azithromycin).
• Discussion with a Sexual Health physician or microbiologist recommended prior to testing for this reason (many laboratories will decline testing without this).

Request M. genitalium NAAT

NAAT on a vaginal swab (self- or clinician-collected) or endocervical swab. The Aptima system can be used; chlamydia and gonorrhoea NAAT can be performed on same swab.

• Excellent sensitivity – a negative test on a well-collected sample makes the diagnosis very unlikely
• Excellent specificity – a positive test reliably detects the organism, but doesn’t necessarily imply it is the cause of symptoms
• First void urine is second line in women due to lower sensitivity.

NAAT on first void urine or urethral swab are the only accepted samples in men.

• Similar sensitivity and specificity to above.

• Outside the context of contact tracing, avoid testing in asymptomatic people, including anorectal testing in MSM, as asymptomatic carriage is common and of uncertain significance.
• Detection in the oropharynx/throat is very uncommon, so oropharyngeal swabs are not accepted.

Many laboratories will test for macrolide (azithromycin) resistance +/- fluoroquinolone resistance when testing for M. genitalium. Interpretation and management of results can be complex and should be in conjunction with a Sexual Health physician.