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Read Now: News and Research From ICAAC 2014

MG: An Emerging Sexually Transmitted Infection

October 9, 2013

The bacterium Mycoplasma genitalium (MG) is sexually transmitted and can cause inflammation of the urinary and genital tracts in men and women. This germ may also be linked to other problems, including some cases of arthritis and, in women, pelvic inflammatory disease and infertility.

MG appears to be spread by unprotected anal or vaginal intercourse, as it can be detected in fluid samples from the penis, rectum and vagina. So far it has not been detected in fluid samples from the throat.

MG, like other sexually transmitted infections (STIs), can cause inflammation of delicate genital tissue. Such inflammation can make the genitals more susceptible to infection with other STIs, including HIV.

In high-income countries, overall rates of MG infection appear to be low, ranging between 1% and 3%. Several studies have found that rates of MG infection tend to be greater among people who seek care for STIs.


Symptoms

Urethritis is an inflammation of the tube (urethra) that carries urine out of the body. Common causes of urethritis are chlamydia and gonorrhea. However, testing of urine and other samples can fail to detect possible causes of urethritis. In such cases, and depending on the degree of distress caused by symptoms, some doctors may treat their patients with a presumed diagnosis of urethritis caused by MG and/or other STIs. In women, MG can cause inflammation of the urethra and cervix (cervicitis) and likely the uterus and the fallopian tubes.

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Symptoms of urethritis in men can include one or more of the following:

  • frequent urination or the feeling of having to urinate frequently
  • a burning sensation while urinating
  • pain during intercourse or on ejaculation
  • discharge from the penis

Symptoms of cervicitis and urethritis in women can include one or more of the following:

  • abdominal pain
  • vaginal pain
  • frequent urination or the feeling of having to urinate frequently
  • pain during intercourse
  • a burning sensation while urinating
  • discharge from the vagina
  • abnormal vaginal bleeding -- after intercourse, after menopause, between periods


Testing

MG is difficult to grow on a culture in the laboratory, meaning that many patients with an MG infection will have false-negative results for their culture. Some labs may have access to specialized tests that can multiply and then detect the genetic material or DNA of MG. Such tests are called nucleic acid amplification tests (NAAT).


Distribution by Gender: MG in Men

Here are several studies that sought to assess the incidence (new cases, usually with symptoms) and prevalence (existing cases) of MG among men in high-income countries:

  • London, UK
    In a study with 438 men who have sex with men (MSM), researchers found that about 7% had MG. HIV-positive MSM were significantly more likely (nearly eight-fold) to have MG infection compared to HIV-negative MSM. Among HIV-positive men, MG was more common than the bacteria that cause gonorrhea and chlamydia.
  • Oslo, Norway
    Researchers tested fluid samples from the anus/rectum, penis and throat of 1,778 MSM. They found that 5% had MG; in 70% of these men, it was found in samples taken from the anus/rectum.
  • Sydney, Australia
    In a study of 1,182 men, 8% tested positive for MG.
  • New Orleans, U.S.
    In a study of people who visited a sexual health clinic, researchers found the following rates of MG infection among men who tested negative for chlamydia and gonorrhea:
    • 25% of 97 men with urinary tract symptoms
    • 7% of 184 men without urinary tract symptoms

    At the same clinic, 35% of men who were co-infected with chlamydia and who had urinary tract symptoms also had MG co-infection. Among those with urinary tract symptoms due to gonorrhea, 14% were co-infected with MG.


Distribution by Gender: MG in Women

Here are several studies that sought to assess the incidence (new cases, usually with symptoms) and prevalence (existing cases) of MG among women in high-income countries:

  • Melbourne, Australia
    In this study of 1,110 women aged 16 to 25 years, only 1.3% had detectable MG.
  • Sydney, Australia
    In this study of 527 women, 4% had MG.
  • Chapel Hill, U.S.
    In a study done in North Carolina with 381 women, MG was found in nearly 20%.
  • Malmo, Sweden
    In this study of 5,519 tested women, only 2% had MG.
  • London, UK
    In a study of 2,378 young women, researchers found that about 3% had MG.


Treatment Options

Regimens for the treatment of MG can vary depending on the region or medical centre and the severity of the disease. In clinical trials comparing the antibiotics azithromycin and doxycycline, azithromycin resulted in more cures. However, those trials were done several years ago and since then MG may have acquired more tolerance and even resistance to azithromycin. Based on reports and clinical trials, there are at least two possible regimens of azithromycin that doctors can consider, as follows:

  • azithromycin single treatment: one dose of 1 gram taken orally
  • azithromycin extended treatment: 500 mg on the first day followed by 250 mg per day for the next four days

Unfortunately, these two regimens have not been compared against each other in clinical trials so doctors are not certain if one is better than the other.

There is also a 2-gram, extended-release formulation of azithromycin (sold as Zmax SR by Pfizer). However, no data on the effectiveness of this dose on MG has been reported.

Increasingly, there have been reports of treatment failure when a single 1-gram dose of azithromycin is used in MG infection. In such cases, some STI experts suggest the use of another antibiotic, moxifloxacin (Avelox), given as 400 mg once daily for between seven to 10 days.

However, it is important to note that reports of MG resistant to both azithromycin and moxifloxacin have been documented.

Our next CATIE News bulletin will focus on antibiotic resistance by MG and a possible emerging therapy.


Acknowledgement

We thank Marc Steben M.D., Institut national de santé publique du Québec, for his helpful discussion, research assistance and expert review.


Resource

STIs: What Role Do They Play in HIV Transmission? -- Prevention in Focus


References

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  2. Cazanave C, Manhart LE, Bébéar C. Mycoplasma genitalium, an emerging sexually transmitted pathogen. Médecine et maladies infectieuses. 2012 Sep;42(9):381-92.
  3. Chrisment D, Machelart I, Wirth G, et al. Reactive arthritis associated with Mycoplasma genitalium urethritis. Diagnostic Microbiology and Infectious Disease. 2013; in press.
  4. Chrisment D, Charron A, Cazanave C, et al. Detection of macrolide resistance in Mycoplasma genitalium in France. Journal of Antimicrobial Chemotherapy. 2012 Nov;67(11):2598-601.
  5. Hamasuna R. Mycoplasma genitalium in male urethritis: diagnosis and treatment in Japan. International Journal of Urology. 2013 Jul;20(7):676-84.
  6. Reinton N, Moi H, Olsen AO, et al. Anatomic distribution of Neisseria gonorrhoeae, Chlamydia trachomatis and Mycoplasma genitalium infections in men who have sex with men. Sexual Health. 2013 Jul;10(3):199-203.
  7. McGowin CL, Annan RS, Quayle AJ et al. Persistent Mycoplasma genitalium infection of human endocervical epithelial cells elicits chronic inflammatory cytokine secretion. Infection and Immunity. 2012 Nov;80(11):3842-9.
  8. Gatski M, Martin DH, Theall K, et al. Mycoplasma genitalium infection among HIV-positive women: prevalence, risk factors and association with vaginal shedding. International Journal of STD and AIDS. 2011 Mar;22(3):155-9.
  9. Moi H, Reinton N, Moghaddam A. Mycoplasma genitalium in women with lower genital tract inflammation. Sexually Transmitted Infections. 2009 Feb;85(1):10-4.
  10. Gillespie CW, Manhart LE, Lowens MS, et al. Asymptomatic urethritis is common and is associated with characteristics that suggest sexually transmitted etiology. Sexually Transmitted Diseases. 2013 Mar;40(3):271-4.
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  12. Bradshaw CS, Chen MY, Fairley CK. Persistence of Mycoplasma genitalium following azithromycin therapy. PLoS One. 2008;3(11):e3618.
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  14. Seña AC, Lensing S, Rompalo A, et al. Chlamydia trachomatis, Mycoplasma genitalium, and Trichomonas vaginalis infections in men with nongonococcal urethritis: predictors and persistence after therapy. Journal of Infectious Diseases. 2012 Aug 1;206(3):357-65.
  15. Oakeshott P, Aghaizu A, Hay P, et al. Is Mycoplasma genitalium in women the "New Chlamydia"? A community-based prospective cohort study. Clinical Infectious Diseases. 2010 Nov 15;51(10):1160-6.
  16. Manhart LE, Gillespie CW, Lowens MS, et al. Standard treatment regimens for nongonococcal urethritis have similar but declining cure rates: a randomized controlled trial. Clinical Infectious Diseases. 2013 Apr;56(7):934-42.
  17. Short VL, Totten PA, Ness RB, et al. Clinical presentation of Mycoplasma genitalium infection versus Neisseria gonorrhoeae infection among women with pelvic inflammatory disease. Clinical Infectious Diseases. 2009 Jan 1;48(1):41-7.
  18. Edlund M, Blaxhult A, Bratt G. The spread of Mycoplasma genitalium among men who have sex with men. International Journal of STD and AIDS. 2012 Jun;23(6):455-6.
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  20. Couldwell DL, Tagg KA, Jeoffreys NJ, et al. Failure of moxifloxacin treatment in Mycoplasma genitalium infections due to macrolide and fluoroquinolone resistance. International Journal of STD and AIDS. 2013 Oct;24(10):822-8.
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This article was provided by Canadian AIDS Treatment Information Exchange. It is a part of the publication CATIE News. Visit CATIE's Web site to find out more about their activities, publications and services.
 

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