Mycoplasma genitalium

Mycoplasma genitalium (MG) is a sexually transmitted bacterium only detectable by nucleic acid amplification tests (NAAT). It causes urethritis in men, cervicitis in women, and asymptomatic rectal infection. It is associated with pelvic inflammatory disease (PID) and is a possible cause of preterm delivery, spontaneous abortion and tubal infertility.

Most laboratories now offer NAAT testing for M. genitalium or can forward to others such as Molecular Microbiology at the Royal Women’s Hospital or the Victorian Infectious Diseases Reference Laboratory. Some NAA tests also detect a mutation conferring resistance to macrolides such as azithromycin.

In men, a first void urine specimen appears more sensitive than a urethral swab. A urine specimen for MG should be performed in all men with non-gonococcal urethritis (NGU). See urethritis guideline.

In women, a vaginal swab is the most sensitive specimen but first void urine or cervical swabs can be used. Women who present with cervicitis or PID should be tested for MG. See vaginal discharge guideline.

Men who have sex with men (MSM)
Asymptomatic rectal infection is common. Several studies show no significant association between MG and proctitis, although cases of proctitis in which M.genitalium is the sole pathogen detected have been reported.

Asymptomatic people 
Sexual contacts of MG, particularly those in a continuing relationship with an infected partner, should be offered testing. MSM require urine and anorectal swabs. Throat swabs are unnecessary as pharyngeal infection is rare (1%). Screening other asymptomatic individuals for M. genitalium is currently not recommended.


Macrolide resistance mutations are detected in approximately 80% of MSM and 50% of heterosexual men and women infected with MG at Melbourne Sexual Health Centre (MSHC). Infections susceptible to azithromycin develop detectable de novo resistance in 12% of cases treated with azithromycin. To improve treatment efficacy and reduce selection of resistance MSHC developed a sequenced resistance-guided treatment strategy based on the macrolide-resistance profile of M.genitalium. This treatment strategy is now in the national guidelines. ASHA Mg guidelines

To avoid the selection of macrolide resistance, treat urethritis, cervicitis and proctitis with one week of doxycycline 100mg bd, instead of azithromycin. All patients with these syndromes should be tested for MG and recalled if positive. Other MG-infected patients (eg sexual partners) should also pre-treated with doxycycline which lowers the bacterial load,1 increasing the likelihood of cure with a second antibiotic.2-4 Doxycycline alone only cures 30% of infections.5

Based on evidence of synergy MSHC is now evaluating combination therapy for MG

For MG infections known or suspected to be macrolide-susceptible treat with
  • doxycycline 100mg bd, 7 days, followed immediately by
  • 4 days of combination therapy comprising: azithromycin 1g stat followed by 500mg daily for another three days (2.5g total) together with doxycycline 100mg bd for 4 days.

For MG infections known or suspected to be macrolide resistant treat with
  • doxycycline 100mg bd, 7 days, followed immediately by
  • 7 days of combination therapy comprising: moxifloxacin 400mg daily together with doxycycline 100mg bd for seven days
Moxifloxacin is not approved by the Therapeutic Goods Administration (TGA) for this infection and may cause significant side-effects including diarrhoea or tendonitis. We recommend discussing this with patients. Pharmacies typically charge over $70 for five tablets. There are limited efficacy data and no data for treatment courses of less than seven days.6

Note: MG infections already treated with azithromycin on the same day as the MG test may be cured but confirm this with a test of cure at least three weeks later. If treatment fails, resistance is likely, particularly if reinfection is unlikely. Clinicians with no access to resistance testing can assume resistance in azithromycin treatment failures. 

Test of cure is essential in managing all MG infections because of the risk of persisting, asymptomatic, resistant infection. The ideal time is three weeks (minimum two) after completing antimicrobial therapy. If symptoms have persisted or rebounded to similar intensity, treatment failure due to resistance is likely, but reinfection is also possible.

Sexual partners
Testing, and treating infected partners is recommended, particularly in a continuing relationship. Given the high prevalence of macrolide resistance and need for moxifloxacin in cases with resistance, discuss with patients both the benefits of treatment and the risk of uncommon but serious side effects. Infection rates in contacts are 40–50% in women and MSM (mostly rectal infection) and 30% in heterosexual men.
M.genitalium associated PID
Routine PID treatment is not likely to adequately treat Mg-associated PID and and combination therapy with moxifloxacin (400mg daily) together with doxycycline (100mg bd) for 14 days is recommended. 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 and pristinamycin may be recommended.

Resistance to fluoroquinolones (eg moxifloxacin) was detected in 20% of infections in Melbourne in 2016-187 and so moxifloxacin treatment-failures are expected. Pristinamycin may be effective when quinolones have failed or cannot be used. It has been used at MSHC at a dose of 1g tds combined with doxycycline 100mg bd for 10 days and appears to cure 70 - 80% of macrolide-resistant infections.8 This is available through hospital pharmacies, using the Special Access Scheme of the TGA. Global shortages have been experienced at the end of 2019 and if pristinamycin is not available limited case reports support the use of minocycline 100mg twice daily for 14 days.


  1. Read TRH, Fairley CK, Murray GL, Jensen JS, Danielewski J, Worthington K, Doyle M, Mokany E, Tan L, Chow EPF, Garland SM, Bradshaw CS.Outcomes of Resistance-guided Sequential Treatment of Mycoplasma genitalium Infections: A Prospective Evaluation.Clin Infect Dis. 2019 Feb 1;68(4):554-560.
  2. Bissessor M, Tabrizi SN, Twin J, et al. Macrolide resistance and azithromycin failure in a Mycoplasma genitalium-infected cohort and response of azithromycin failures to alternative antibiotic regimens. Clinical infectious diseases : an official publication of the Infectious Diseases Society of America 2015;60:1228-36.
  3. Guschin A, Ryzhikh P, Rumyantseva T, Gomberg M, Unemo M. Treatment efficacy, treatment failures and selection of macrolide resistance in patients with high load of Mycoplasma genitalium during treatment of male urethritis with josamycin. BMC infectious diseases 2015;15:40.
  4. Read TRH, Fairely CK, Tabrizi S, Bissessor M, Vodstrcil L, Chow EPF, Grant M, Danielewski J, Garland SM, Hocking JS, Chen MY, Bradshaw CS. Azithromycin 1.5g over five days compared to 1g single dose in urethral Mycoplasma genitalium: impact on treatment outcome and resistance Clinical Infectious Diseases 2016.
  5. Jensen JS, Bradshaw C. Management of Mycoplasma genitalium infections - can we hit a moving target? BMC infectious diseases 2015;15:343.
  6. Li Y, Le WJ, Li S, Cao YP, Su XH. Meta-analysis of the efficacy of moxifloxacin in treating Mycoplasma genitalium infection. International journal of STD & AIDS 2017:956462416688562.
  7. Murray GL, Bradshaw CS, Bissessor M, et al. Increasing Macrolide and Fluoroquinolone Resistance in Mycoplasma genitalium. Emerg Infect Dis 2017;23:809-12.
  8. Bradshaw CS, Read TRH, Fairley CK, Jensen J, Danielewski J, Tabrizi S. Efficacy of pristinamycin for treatment resistant Mycoplasma genitalium. Australasian Sexual Health Conference. Adelaide2016.

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 September 2019