Genital Mycoplasmas

Mycoplasma hominis
Mycoplasma hominis

Mycoplasmas, the smallest self-replicating organisms, are commonly found in the genitourinary tract.1 However, they are occasionally found outside this environment, usually in immunocompromised people.1 Among the 6 genital mycoplasmas located in the genitourinary tract, 4 (Mycoplasma hominis, M genitalium, Ureaplasma parvum, and U urealyticum) cause clinical infection.1

Genital Mycoplasma Cause & Presentation

Genital mycoplasmas caused by both Mycoplasma and Ureaplasma species are sexually transmitted; however, their role in genital tract disease varies significantly.1 

U urealyticum and M genitalium cause acute and persistent nongonococcal urethritis (NGU), with M genitalium being the second leading cause of NGU after Chlamydia trachomatis.1,2 Although M hominis and U parvum are found in the male genital tract, neither are causative pathogens of NGU.1,2 Clinical manifestations of mycoplasmas in men are similar regardless of the underlying pathogen, with symptoms including dysuria, irritation, urgency, meatal pruritus, and urethral discharge.1,3 Evidence of an etiologic role for mycoplasmas in urethritis in women is lacking; however, M hominis and U urealyticum are loosely associated with this condition.4

M genitalium causes endocervicitis, as evidenced by cervical tenderness, abnormal vaginal discharge, and/or intermenstrual bleeding.1,3 However, more than half of women who test positive for M genitalium are asymptomatic.3 In addition, M genitalium and to a lesser extent M hominis and Ureaplasma species are associated with pelvic inflammatory disease (PID).1 

When M hominis is present in vaginal fluid, it is strongly associated with bacterial vaginosis.1 Vaginal discharge with or without a fishy odor is a common complaint, but a portion of individuals are asymptomatic.5 In genitourinary tract syndromes such as PID, the contribution of M hominis to symptoms remains unclear.1

High levels of M hominis in the vagina strongly correlate with shedding of HIV and may be a risk factor for transmission of the virus.1 Urogenital infection with M genitalium has been found to be associated with increased HIV shedding, especially in patients not undergoing treatment with antiretroviral therapy.6 In addition, M genitalium can cause rectal infections (most of which are asymptomatic), with 1% to 26% of cases occurring in men who have sex with men and 3% of cases occurring in women.6 

Genital mycoplasmas can cause systemic infections, most often presenting as sepsis syndrome, and M hominis is the most common associated pathogen.1 Postoperative wound infections, postpartum fever, and septic arthritis caused by M hominis are well documented, and cases of endocarditis, pneumonia, and abscesses have also been reported.1 

Diagnostic Workup & Physical Examination

Clinical evaluation based on patient presentation and history should include a pelvic examination, if necessary, and sampling of vaginal or penile discharge, first-void urine, and/or rectal and endocervical swabs.3,5 

The following clinical situations lead to a higher degree of suspicion for genital mycoplasmas as the causative agent:

  • Pyelonephritis with negative standard cultures and failed antibiotic treatment4
  • Persistent symptoms of lower urinary tract infection4
  • Recurrent or persistent NGU in men testing negative for infections with C trachomatis7
  • Symptoms of cervicitis with negative test results for bacterial vaginosis and trichomoniasis7
  • Culture-negative cases of well-documented infection with properly collected samples in the absence of antibiotic treatment1

Genital mycoplasmas are frequently identified using culture systems; however, this screening modality is time-consuming. Ureaplasma species and M hominis require 2 to 5 days to grow, and M genitalium can takes up to 8 weeks to grow.6 Culturing, especially for M genitalium, has therefore lost popularity owing to the development of newer technologies for the diagnosis of sexually transmitted infections (STIs).2

Nucleic acid amplification tests (NAATs) are the gold standard for identification of STIs.2,6 They are more sensitive than other diagnostic methods such as culture, nucleic acid hybridization, or antigen detection tests.2,9 NAAT is noninvasive, requiring a vaginal swab or first-void urine sample.2

Use of multiplex real-time polymerase chain reaction (RT-PCR) assays has made it easier for clinicians to test for more than 1 causative organism. These newer assays — which have improved detection sensitivity, decreased amplification time, and lowered labor and reagent costs compared with conventional PCR — are cost effective.2 Authors of a study that examined the sensitivity and specificity of RT-PCR assays in the detection of STIs showed RT-PCRs to be 100% sensitive and specific for M genitalium.2 

Another benefit to NAATs is that they can distinguish between the Ureaplasma species U urealyticum and U parvum.2,9 The results of a 2018 study revealed that approximately 5% of women of childbearing age are colonized with U urealyticum compared with approximately 30% who are colonized with U parvum.9 Distinguishing between these 2 species prevents unnecessary treatment of U parvum, which is more of a colonizing pathogen than a causative one.2 Some diagnostic testing kits may not be able to distinguish between Ureaplasma species, necessitating additional testing.2

Differential Diagnosis of Genital Mycoplasmas

The symptomatology of genital mycoplasma infections is similar to that of infection with other sexually transmitted pathogens, such as C trachomatis and Neisseria gonorrhoeae). For this reason, NAATs are essential for making an accurate diagnosis.2 In men with symptoms of urethritis, clinicians should consider chronic prostatitis or chronic pelvic pain syndrome as potential causes.7 Bacterial or yeast infections should also be ruled out.8

Risks & Complications

In men, infection with M genitalium has been linked to chronic complications such as prostatitis, epididymitis, and infertility; however, there are insufficient data to establish this pathogen as causative.6 Authors of a large meta-analysis reported that the prevalence of U urealyticum and M hominis was higher among infertile men compared with fertile men.10 There is also evidence to suggest that infection with U urealyticum affects sperm quality.2

Women with M genitalium infection have a 2-fold increased risk for spontaneous abortion, preterm delivery, infertility, cervicitis, and PID.6 Results of a meta-analysis revealed a higher prevalence of U urealyticum, M hominis, and M genitalium in infertile women compared with fertile women.10

Although the evidence is mixed, there appears to be a link between pregnancy complications —such as premature rupture of membranes (PROM), spontaneous abortion, and preterm delivery — and colonization with U urealyticum and M hominis.8 Colonization with M hominis has been associated with higher rates of PROM compared with colonization with U urealyticum.11 Detection of U urealyticum in vaginal cultures has been linked to chorioamnionitis.8 Infection with U urealyticum alone or coinfection with Candida has been reported to increase the risk of chorioamnionitis and preterm birth before 30 weeks.8 

An increased level of proinflammatory biomarkers in the amniotic fluid has also been linked to adverse pregnancy outcomes; this increase was associated with M hominis and U urealyticum but not M genitalium.11 Neonates are frequently colonized with Ureaplasma species and less frequently M hominis in both the genital and respiratory tracts after vaginal birth.1 The primary risk factor for colonization is exposure to vaginal secretion at birth,  and female infants are more likely to be colonized than male infants.1 

Despite the abundance of evidence regarding risks and complications associated with M genitalium, long-term effects of asymptomatic infection among men and women are unknown.6 


1. Martin DH. Genital mycoplasmas: Mycoplasma genitalium, Mycoplasma hominis, and Ureaplasma species. In: Mandell, Douglas, and Bennett’s Principles and Practice of Infectious Diseases. 9th ed. Elsevier; 2020:2340-2343. 

2. Choe HS, Lee DS, Lee SJ, et al. Performance of Anyplex ™ II multiplex real time PCR for the diagnosis of seven sexually transmitted infections: comparison with currently available methods. Int J Infect Dis. 2013;17:E1134-E1140. doi:10.1016/j.ijid.2013.07.011 

3. Ona S, Molina RL, Diouf K. Mycoplasma genitalium: an overlooked sexually transmitted pathogen in women? Infect Dis Obstet Gynecol. 2016;2016:4513089. doi:10.1155/2016/4513089

4. Combaz-Sohnchen N, Kuhn A. A systematic review of mycoplasma and ureaplasma in urogynaecology. Geburtshilfe Frauenheilkd. 2017;77(12):1299-1303. doi:10.1055/s-0043-119687

5. Abou Chacra L, Fenollar F, Diop K. Bacterial vaginosis: what do we currently know? Front Cell Infect Microbiol. 2022;11:672429. doi:10.3389/fcimb.2021.672429

6. Mycoplasma genitalium – STI Treatment Guidelines, 2021. Centers for Disease Control and Prevention. Reviewed July 22, 2021. Accessed November 21, 2022.

7. Diseases characterized by urethritis and cervicitis – STI Treatment Guidelines, 2021. Centers for Disease Control and Prevention. Reviewed September 22, 2022. Accessed November 21, 2022. 

8. Matasariu DR, Ursache A, Agache A, et al. Genital infection with Ureaplasma urealyticum and its effect on pregnancy. Exp Ther Med. 2022;23(1):89. doi:10.3892/etm.2021.11012

9. Leli C, Mencacci A, Latino MA, et al. Prevalence of cervical colonization by Ureaplasma parvum, Ureaplasma urealyticum, Mycoplasma hominis and Mycoplasma genitalium in childbearing age women by a commercially available multiplex real-time PCR: an Italian observational multicentre study. J Microbiol Immunol Infect. 2018;51(2):220-225. doi:10.1016/j.jmii.2017.05.004

10. Moridi K, Hemmaty M, Azimian A, Fallah MH, Khaneghahi Abyaneh H, Ghazvini K. Epidemiology of genital infections caused by Mycoplasma hominis, M. genitalium and Ureaplasma urealyticum in Iran; a systematic review and meta-analysis study (2000–2019). BMC Public Health. 2020;20(1):1020. doi:10.1186/s12889-020-08962-5 

11. Noda-Nicolau NM, Tantengco OAG, Polettini J, et al. Genital mycoplasmas and biomarkers of inflammation and their association with spontaneous preterm birth and preterm prelabor rupture of membranes: a systematic review and meta-analysis. Front Microbiol. 2022;13:859732. doi:10.3389/fmicb.2022.859732

Author Bio

Emilie White, PharmD, is a clinical pharmacist with more than a decade of experience providing direct patient care in a hospital setting. She received her Doctor of Pharmacy degree from Massachusetts College of Pharmacy and Health Sciences. After graduation, she completed a postgraduate pharmacy residency. Her background includes caring for critical care, internal medicine, and surgical patients.