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Mycoplasma genitalium: A pelvic inflammatory disease pathogen that needs attention
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Chlamydia trachomatis is the leading bacterial sexually transmitted infection in the world. It is a well-known cause of cervicitis and pelvic inflammatory disease in women, with attendant risk for severe sequelae, including chronic pelvic pain, infertility and ectopic pregnancy.
Health care programs in the United States and Europe have actively targeted teenage and young adult females for education, screening and treatment with the goal of preventing long-term complications and reducing prevalence. It is encouraging that in areas where screening and treatment programs for C. trachomatis have been instituted, rates of pelvic inflammatory disease (PID) and ectopic pregnancy have decreased. This is despite a coincident detection of increased rates of chlamydial infection that can likely be explained by enhanced sensitivity of diagnostic chlamydial nucleic acid amplification tests and increased screening of patients at risk. Fortunately, azithromycin and doxycycline remain efficacious against C. trachomatis with high microbiological and clinical cure rates.
Proper testing needed
Many patients with cervicitis and/or PID test negative for C. trachomatis andNeisseria gonorrhoeae. Recent data indicate a need to consider Mycoplasma genitalium as a cause of illness in these patients, as well as its potential to be a co-pathogen that may not respond to doxycycline. Although M. genitalium has been a well-known cause of nongonococcal urethritis in men, discrepant results have been reported regarding its role as a cause of female cervicitis and PID. However, data from a cross-sectional case-control study performed in Malmö, Sweden, clearly indicate that M. genitalium is an independent and strong risk factor for both cervicitis and PID.
Bjartling and colleagues tested 5,519 female patients who presented to a gynecological outpatient service with various gynecological symptoms during a 5-year period. Their ages ranged from 15 to 52 years (mean, 26 years). The prevalence of M. genitalium was 2.1% and of C. trachomatis was 2.8%, with dual infections being noted in 3.8%. Younger women had higher rates of both C. trachomatis and M. genitalium, with the highest rates of C. trachomatis being observed in women aged 15 to 20 years, and the highest rates of M. genitalium being observed in women aged 20 to 24 years. Both cervicitis and PID were diagnosed more frequently in M. genitalium-positive women than in negative controls (cervicitis: 22.3% vs. 7%, P<.001; PID: 4.9% vs. 0.6%, P=.01). Women infected with C. trachomatis had higher rates of cervicitis (33.4%; P<.001) and PID (18.3%; P <.001) than those with M. genitalium.
Toni Darville
It is important to note that infection with M. genitalium led to less frequent and less severe symptoms than C. trachomatis. Abnormal vaginal discharge, post-coital bleeding and painful urination were all more frequent in C. trachomatis-positive women compared with M. genitalium-positive women. In fact, the only self-reported symptom that was higher in M. genitalium-positive women than controls was post-coital bleeding (22.3% vs. 11.9%; P=.008). Additionally, clinical signs such as cervical tenderness, elevated C-reactive protein and fever were more frequent in C. trachomatis-positive women than women infected with M. genitalium.
A study in London revealed that female students who screened positive for M. genitalium at enrollment had a nonsignificant increased rate of symptomatic PID develop during 12 months of follow-up. An additional study from the United Kingdom detected an independent association of M. genitalium with PID among women from STI clinics. In a previous large multicenter PID Evaluation and Clinical Health (PEACH) study conducted in the United States, M. genitalium was independently associated with endometritis (OR=3; 95% CI, 1.5-6.1), and there was a nonsignificant trend toward increased infertility, recurrent PID and chronic pelvic pain after M. genitalium infection. Interestingly, in the Swedish study by Bjartling and colleagues, both M. genitalium-positive (13.3%) and C. trachomatis-positive (9.9%) women were less likely to be pregnant (P=.005 and P=.001, respectively) than the controls (26.6%).
High prevalence among teens
These studies indicate that although M. genitalium infection may cause fewer and less severe symptoms than C. trachomatis, it is an independent risk factor for PID and is associated complications. It is possible that asymptomatic infection with this organism could also lead to reproductive morbidities, as has been suggested with silent C. trachomatis infections. Prevalence rates for M. genitalium infection in teens and women in high- or low-risk populations worldwide range from 7.3% to 2%, respectively, which fall in between those of C. trachomatis and N. gonorrhoeae.
Treatment studies of males with M. genitalium urethritis reveal azithromycin is superior to doxycycline. A commercially available diagnostic test for M. genitalium is sorely needed to further investigate the role of this organism in symptomatic PID and subclinical endometritis, and to determine whether current recommended therapies for PID should be altered when M. genitalium is detected.
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Disclosure: Darville reports no relevant financial disclosures.