Mycoplasma genitalium


Mycoplasma genitalium (Mg) is a sexually transmitted bacterium that is difficult to culture and detection relies on the use of PCR assays. It is a cause of urethritis in men, cervicitis in women, and rectal infection, although the latter is commonly asymptomatic. Recent evidence indicates it is associated with pelvic inflammatory disease (PID) and is a possible cause of tubal factor infertility. 

Currently there are no commercially available diagnostic assays to detect M.genitalium,  however some reference laboratories, such as the Molecular Microbiology Laboratory of the Royal Women’s Hospital and the Victorian Infectious Diseases Reference laboratory (VIDRL), perform NAAT testing for M.genitalium based on in house assays. 

In men, a first void urine specimen appears more sensitive than a urethral swab. A urine specimen for M.genitalium should be performed in all men who present with non-gonococcal urethritis. See MSHC treatment guideline on urethritis.

In women, first void urine or cervical or vaginal swabs can be used. Women who present with clinically apparent cervicitis or PID should be tested for M.genitalium. See MSHC treatment guideline on vaginal discharge.

Men who report sex with men 
Men who report sex with men who present with symptoms of proctitis should be tested for rectal M.genitalium using an anal swab. See MSHC treatment guideline on proctitis.
Screening of asymptomatic individuals for M.genitalium from the pharynx, urethra, cervix or rectum is not recommended, however testing of all sexual contacts of M.genitalium is recommended (see below). 


Uncomplicated M.genitalium infection

  • 1g azithromycin orally  Or
  • 500mg azithromycin stat orally followed by 250mg daily for 4 days

1 gram of azithromycin is significantly more effective against M.genitalium than doxycycline, however resistance to azithromycin is rapidly emerging internationally. In 2014 approximately 40% of MG strains detected at MSHC harboured macrolide resistance mutations and failed 1g of azithromycin. A longer course of azithromycin (500mg stat followed by 250mg daily for 4 days) can be used as an alternative regimen but does not appear to be significantly superior to 1g. Persons failing 1g of azithromycin generally do not benefit from further treatment with the extended regimen.  

It is essential that treatment is followed by a test of cure for Mg 2-4 weeks following treatment. Performing a repeat test within two weeks of azithromycin may result in detection of non-viable DNA. If treatment failure occurs, exclude reinfection from an untreated partner. If reinfection may have occurred retreat both with azithromycin and arrange another test of cure 2-4 weeks following retreatment.

If reinfection is unlikely and azithromycin resistance is suspected as the cause of failure discuss the case with a sexual health physician at MSHC. Second line agents such as moxifloxacin have limited availability in the community and treatment at a specialist service such as MSHC may be required.  

M.genitalium associated PID
Women with Mg associated PID should be discussed with a sexual health physician as routine PID treatment is not likely to adequately treat Mg-associated PID and moxifloxacin may be required.  See MSHC treatment guideline on PID. 

M.genitalium in pregnancy
Azithromycin is category B1 and can be prescribed in pregnancy. If a patient is pregnant and considered at risk of resistant M.genitalium infection this case should be discussed with a sexual health physician. 

The content of these treatment guidelines is for information purposes only. The treatment guidelines are generic in character and should be applied to individuals only as deemed appropriate by the treating practitioner on a case by case basis. Alfred Health, through MSHC, does not accept liability to any person for the information or advice (or the use of such information or advice) which is provided through these treatment guidelines. The information contained within these treatment guidelines is provided on the basis that all persons accessing the treatment guidelines undertake responsibility for assessing the relevance and accuracy of the content and its suitability for a particular patient. Responsible use of these guidelines requires that the prescriber is familiar with contraindications and precautions relevant to the various pharmaceutical agents recommended herein.

Last Updated December 2014