Mycoplasma Genitalium

Mycoplasma genitalium (MG) is a bacteria that causes non-gonococcal urethritis. It is a sexually transmitted infection. There are developing problems with antibiotic resistance, particularly with azithromycin.

Most cases of MG do not cause symptoms. The presentation is very similar to chlamydia, and patients may be infected with both organisms. Urethritis is a key feature.

Mycoplasma genitalium infection may lead to:

  • Urethritis
  • Epididymitis
  • Cervicitis
  • Endometritis
  • Pelvic inflammatory disease
  • Reactive arthritis
  • Preterm delivery in pregnancy
  • Tubal infertility



Traditional cultures are not helpful in isolating MG, as it is a very slow-growing organism. Therefore, testing involves nucleic acid amplification tests (NAAT) to look specifically for the DNA or RNA if the bacteria.

The samples recommended by BASHH guidelines (2018) are:

  • First urine sample in the morning for men
  • Vaginal swabs (can be self-taken) for women

The guideline recommends checking every positive sample for macrolide resistance, and performing a “test of cure” after treatment in every positive patient.



The BASHH guidelines (2018) recommend a course of doxycycline followed by azithromycin for uncomplicated genital infections:

  • Doxycycline 100mg twice daily for 7 days then;
  • Azithromycin 1g stat then 500mg once a day for 2 days (unless it is known to be resistant to macrolides)


Moxifloxacin is used as an alternative or in complicated infections. Azithromycin alone is used in pregnancy and breastfeeding (remember doxycycline is contraindicated).


Last updated July 2020