Mycoplasma genitalium, an infection that cannot be ignored by infertile patients

The "Lancet China Maternal and Child Health 70 Years Study" released in June 2021 pointed out that the proportion of infertile patients among women of childbearing age in my country has increased from 12% in 2007 to 18% in 2020, and the number of assisted reproductive technology (ART) cycles has exceeded 1 million times. Reproductive tract pathogen infection is one of the important causes of infertility. The most common are Chlamydia trachomatis, Ureaplasma urealyticum, Neisseria gonorrhoeae and Mycoplasma genitalium infections. In particular, Mycoplasma genitalium is an important pathogen of reproductive tract infection that has gradually been paid attention to in recent years.

Mycoplasma genitalium is an important sexually transmitted pathogen that can cause a variety of male and female reproductive tract diseases. In 1981, Mycoplasma genitalium was first isolated from urethral secretions of patients with non-gonococcal urethritis. It is the smallest known organism with a genome that can replicate itself, with a genome size of only 580kb. Sexual transmission is the main mode of transmission of Mycoplasma genitalium. Recently, a large number of epidemiological studies have shown that the infection rate of Mycoplasma genitalium is gradually increasing, and a holistic understanding of Mycoplasma genitalium infection is needed to facilitate the development of new prevention and control strategies.

1. Prevalence of Mycoplasma genitalium

The infection rate of Mycoplasma genitalium in the general population in developed countries is 1.3%. Among the physical examination population in my country, the infection rate of men is 2.63% and the infection rate of women is 0.53%, which is slightly lower than that of men. There are differences in infection rates in different regions. The infection rate in HIV-infected people is higher than that in healthy people. Surveys in recent years have found that Mycoplasma genitalium infection has increased significantly in infertile women, and the infection rate can reach 5%-6%. The infection is closely related to non-gonococcal urethritis. The positive rate of Mycoplasma genitalium in patients with symptomatic non-gonococcal urethritis is as high as 12%. Male Mycoplasma genitalium infection can lead to prostatitis. Female Mycoplasma genitalium infection can cause mucous cervicitis and endometritis. It is one of the important factors leading to infertility and miscarriage.

2. Clinical manifestations of Mycoplasma genitalium infection

Mycoplasma genitalium is a risk factor for urogenital tract inflammation, infertility and adverse pregnancy outcomes. The main clinical manifestations are frequent urination, urgency, dysuria, redness and swelling of the urethral orifice, perineum or waist and abdominal pain, lower abdominal distension, increased vaginal discharge in women, and scrotal swelling in men. However, most people have no obvious or specific symptoms after being infected with Mycoplasma genitalium, which can be easily overlooked.

3. Clinical diagnosis of Mycoplasma genitalium infection

Pathogen-related tests are the "gold standard" for identifying Mycoplasma genitalium infection. The clinical diagnosis of Mycoplasma genitalium mainly includes isolation culture and molecular biological testing. Isolation culture uses fresh samples such as the patient's urine, semen, vaginal secretions, etc., which are isolated and inoculated on the culture medium. If Mycoplasma genitalium is cultured, the diagnosis can be confirmed. However, due to the long growth cycle of Mycoplasma genitalium, it requires special culture medium, is difficult to isolate and culture, and has a low detection rate. Nucleic acid amplification is currently the only rapid and accurate detection method. The constant temperature PCR method detects pathogen RNA with high sensitivity and good specificity. It can be used for urine, semen, prostatic fluid and various swab specimens.

4. Treatment of Mycoplasma genitalium infection

The macrolide azithromycin is the first-line treatment recommended by most national and international guidelines, and the fluoroquinolone moxifloxacin is the second-line treatment. However, there are more and more reports of resistance and treatment failure to these two types of antimicrobial drugs. Epidemiological surveys show that the resistance rate of Mycoplasma genitalium to macrolide antibiotics is increasing. The Lancet Infectious Diseases reported that the overall resistance rate to macrolide antibiotics was 35.5%, and it increased from 10.0% before 2010 to 51.4% in 2017. The resistance situation to fluoroquinolones is relatively good, with an overall resistance rate of 7.7%, and the resistance prevalence has changed little over time. Other treatment drugs include doxycycline, minocycline, pristinamycin, etc.

Mycoplasma genitalium has attracted widespread attention in the medical community, and the urogenital tract diseases, infertility and miscarriage, as well as other related diseases caused by it are receiving increasing attention.

References:

1. Qiao J, Wang Y, Li X, et al. A Lancet Commission on 70 years of women's reproductive, maternal, newborn, child, and adolescent health in China. Lancet. 2021,397(10293):2497-2536.

2. TullyJG, Taylor-Robinson D, Cole RM, et al. A newly discovered mycoplasma in the human urogenital tract. Lancet. 1981,1(8233):1288-91.

3. Yu J, Zhou Y, Luo H, et al. Mycoplasma genitalium infection in the female reproductive system: Diseases and treatment. Front Microbiol. 2023,14:1098276.

4. GosséM, Lysvand H, Pukstad B, et al. A Novel SimpleProbe PCR Assay for Detection ofMutations in the 23S rRNA Gene Associated with Macrolide Resistance inMycoplasma genitalium in Clinical Samples. J Clin Microbiol. 2016,54(10):2563-7.

5. JensenJS, Cusini M, Gomberg M, et al. 2021 European guideline on the management of Mycoplasma genitalium infections. J Eur Acad Dermatol Venereol. 2022,36(5):641-650.

6. Wang Yudan, Xiong Zhengai. Research progress in the treatment of Mycoplasma genitalium infection. Progress in Clinical Medicine, 2023, 13 (12): 18932-18940.

About the author: Wei Sanhua, Ph.D., is an associate chief physician, associate professor, and master's supervisor at the Reproductive Medicine Center of Tangdu Hospital, Air Force Medical University of the People's Liberation Army of China, a director of the Shaanxi Microbiology Society, and a member of the Chinese Society of Microbiology. He is engaged in reproductive testing.

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