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Mycoplasma genitalium

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What are important characteristics of Mycoplasmoides genitalium?

CHARACTERISTICS

Mycoplasmoides genitalium (Mgen) is a small, facultative, anaerobic bacterium with a characteristic flask shape on electron microscopy. It is the smallest known free-living microoganism (0.2 µm in diameter), in between the size of bacteria and viruses, that is capable of self-replication.

Mgen is from the class Mollicutes and the family Mycoplasmoidaceae. The Mollicute class of bacteria lack rigid cells walls which make them resistant to β-lactam antibiotics, such as penicillin, cephalosporins and carbapenems. Instead of a cell wall, Mgen has a three-layered membrane containing sterol , which is taken up from the environment.

HOST

Humans are the only known host.

CAUSE AND COMPLICATIONS

In males, Mgen is the leading cause of nongonococcal urethritis (NGU) and non-chlamydial non-gonococcal urethritis (NCNGU) which are characterized with dysuria and/or non-spontaneous discharge. It is also strongly associated with epididymitis and chronic prostatitis.

In females, Mgen is the leading cause of mucopurulent cervicitis (MPC), which is the female equivalent of NGU, and is characterized by the presence of yellow or green exudates from the cervix. Mgen is also strongly associated with pelvic inflammatory disease (PID) and bacterial vaginosis in females and may play a minor role in adverse pregnancy outcomes and infertility.

Mgen is known to facilitate HIV transmission.

SIGNS, SYMPTOMS AND ASSOCIATED DISEASE OUTCOMES

Mgen typically causes symptom-free infection in the urinary tract. However, some people may develop urinary issues including:

  • urethral pruritus (itchiness at the tip of the urethra)
  • dysuria (discomfort, pain or a burning sensation when urinating)
  • discharge from the penis or vagina
  • a sudden need to urinate or the need to urinate more frequently than usual
  • painful intercourse
  • painful ejaculation in men
  • non-menstrual vaginal bleeding (i.e., spotting)

Clinical manifestations of Mgen can be similar to those caused by gonorrhea and chlamydia, therefore a visit to a healthcare provider is necessary to determine the cause of urinary problems.

INCUBATION PERIOD

Unknown.

TRANSMISSION & PREVENTION

Mgen is transmitted by vaginal or anal sex with someone who has the infection. A person infected with Mgen can still spread the infection if they do not have symptoms.

Individuals who are sexually active can reduce the risk of infection by:

  • Using condoms correctly
  • Limiting the number of sexual partners
  • Being in a long-term, mutually monogamous relationship with a partner who does not have Mgen

TREATMENT

Antibiotic resistance (particularly to macrolides) complicates the management and treatment of Mgen and increases the risk of persistent infection and transmission. As such, antibiotic resistance determines the choice of treatment for Mgen.

Recommended treatment regimes are listed in the Mgen chapter of the Canadian Guidelines on Sexually Transmitted Infections (2018).

World Health Organization Conditional Recommendations

In 2024, the WHO released updated recommendations for the treatment of Mgen.

Conditional recommendations are made with low certainty in evidence of effects. Please refer to Table 2 in WHO – Recommendations for the treatment of Trichomonas vaginalis, Mycoplasma genitalium, Candida albicans, bacterial vaginosis and human papillomavirus (anogenital warts)(2024) for more information.

IMMUNIZATION & PHROPHYLAXIS

None available.

DIAGNOSTIC TESTING

Routine testing for Mgen is not recommended. Testing for Mgen is only recommended when chlamydia and gonorrhea have been ruled out as a cause of persistent or recurrent urethritis, cervicitis, or pelvic inflammatory disease (PID) following empiric treatment for gonorrhea and chlamydia OR when pre-treatment nucleic acid amplification test (NAAT) or follow-up test of cure (TOC) are negative for chlamydia and gonorrhea.

Serological assays, antigen detection assays, and rapid diagnostic tests are currently not available for Mgen. Culture methods are also not appropriate for the diagnosis of Mgen as they are labour intensive and can take several months. Therefore, current laboratory testing for Mgen uses NAAT. The availability of laboratory testing with NAAT for Mgen varies across provinces and territories; therefore, it is important to check with local laboratories about testing availability, specimen collection, and transportation requirements.

Specimens that are positive for Mgen can be forwarded to the National Microbiology Laboratory (NML) for thedetection of mutations that predict antimicrobial resistance.

For detailed information on antimicrobial resistance testing at the NML, please refer to Molecular Detection of Mutations Associated with Antimicrobial Resistance.

What is happening with current outbreaks of Mycoplasmoides genitalium?

EPIDEMIOLOGY

Global prevalence of Mgen remains unclear due to limited routine testing and insufficient bacterial surveillance. A 2018 systematic review examining studies published between 1991 and 2016 estimated Mgen prevalence to range from 1.3% to 3.9% in the general population, 0.9% among pregnant women, 3.2% among men who have sex with men (MSM), and 15.9% among female commercial sex workers. Prevalence in the general population was similar between men and women. Additional research is needed to better characterize current global prevalence patterns.

Canadian epidemiological data on Mgen are limited, and prevalence estimates vary considerably across studies, population groups, and clinical settings. Although no national or provincial/territorial surveillance systems currently exist for Mgen in Canada, a 2025 scoping review by Copete et al. found Mgen prevalence estimates ranging from 3.0% to 30.3% across eight, Canadian, cross-sectional studies (published between 1980 and 2023). Estimates varied by sex, gender, province, symptom status, and diagnostic specimen type. A summary of prevalence estimates from the eight included studies across different settings, populations, and geographic regions in Canada is provided in Table 1 of the scoping review.

What is the current risk for Canadians from  Mycoplasmoides genitalium?

Mgen is a Risk Group 2 (RG2) pathogen. This means it has moderate risk to individuals and low community risk — the same risk level as pathogenic Escherichia coli (E.coli).

What measures should be taken for a suspected Mycoplasmoides genitalium caser or contact?

M. genitalium is not a national, provincial, or territorial reportable infection in Canada.

Individuals experiencing urinary symptoms or symptoms consistent with an STI should seek medical care for testing and treatment. Individuals diagnosed with Mgen, along with their sexual partners, are advised to use condoms until treatment has been completed by both the individual and their current partners.

Although evidence is insufficient to support routine partner notification for Mgen, current sexual partners of individuals undergoing treatment should receive the same therapy to help prevent reinfection of the index case.