On this page
What is Mycoplasma Genitalium and Hominis?
Genital infections are among the most common gynecological conditions affecting women, and they present a significant diagnostic challenge: different infectious agents can produce remarkably similar symptoms, making precise identification essential for appropriate management.
Mycoplasma infection, a sexually transmitted condition, deserves particular attention because, when unrecognized and untreated, it can progress to Pelvic Inflammatory Disease (PID), a serious condition that can cause permanent damage to the female reproductive organs.
A Unique Microorganism
Mycoplasmas are unusual bacteria with a critically important structural characteristic: they lack a cell wall. This biological feature has major therapeutic implications. Antibiotics that work by inhibiting bacterial cell wall synthesis (the penicillin family and the broader beta-lactam class, including Augmentin/amoxicillin-clavulanate) are completely ineffective against Mycoplasma. This is a common clinical pitfall that must be recognized to avoid therapeutic failure.
Diagnosis is typically established through vaginal swab culture or molecular testing, and treatment requires specifically chosen antibiotics targeting bacteria without cell walls.
Causes and Transmission
The pathogenic agent is a Mycoplasma bacterium, of which multiple species exist. The two species most clinically relevant to genital tract infections are:
Mycoplasma Genitalium
M. genitalium was first identified in 1981 and is now recognized as an important sexually transmitted pathogen. Key characteristics:
- Transmission is almost exclusively sexual, via unprotected vaginal, oral, or anal intercourse.
- Affects both women and men.
- In many infected individuals, particularly men, the infection may remain completely asymptomatic, which significantly facilitates ongoing silent transmission.
- Asymptomatic carriers who engage in unprotected intercourse unknowingly transmit the bacterium, which then colonizes the vaginal epithelium of their partner.
Mycoplasma Hominis
M. hominis is the most common of the two species causing genital tract infections:
- Also transmitted primarily through sexual contact
- Can be a commensal organism, colonizing the vaginal environment without causing symptoms in many women, particularly in those with a healthy immune system
- Symptomatic infection typically arises in the context of immune compromise, significant stress, or systemic illness that disrupts normal host defenses
- Tends to colonize both the genital and urinary tracts, and does so more frequently in women than in men
The Silent Transmission Problem
The greatest risk associated with both Mycoplasma species is the extended window of asymptomatic carriage: in the absence of symptoms, the bacterium continues to be transmitted unknowingly and has time to establish a chronic infection, creating ideal conditions for subsequent complications.
In both species, transmission is primarily sexual, making mechanical barrier methods (condoms) an important preventive measure, although they do not eliminate risk entirely.
Symptoms
In a substantial proportion of infected patients, both men and women, the presence of Mycoplasma produces no symptoms whatsoever. When symptoms are present, they are frequently non-specific and can be easily confused with other, less serious vaginal infections such as bacterial vaginosis or Gardnerella vaginalis infection.
Symptoms of Mycoplasma Genitalium Infection
In Women (Vaginitis/Cervicitis)
- Dyspareunia: pain during sexual intercourse, localized to the lower genital tract
- Abnormal vaginal discharge: which may be mixed with intermenstrual or post-coital spotting (bleeding between periods or after intercourse, a symptom that always warrants medical evaluation)
In Both Sexes (Urethritis)
When the urinary tract is involved, the clinical picture is that of urethritis:
- Mucopurulent urethral discharge (from the penis in men)
- Burning or pain during urination (dysuria)
Symptoms of Mycoplasma Hominis Infection
M. hominis infection typically presents with milder but more persistent symptoms, primarily:
- Vaginal discharge: often the only complaint, appearing throughout the day
- The relatively subtle nature of symptoms contributes to delayed diagnosis and the risk of progression
Symptoms in Men
Men frequently carry Mycoplasma asymptomatically but may develop:
- Urethral discharge
- Burning on urination
- Mild discomfort in the urogenital area
- In some cases, epididymitis or prostatitis
Complications
Complications of Mycoplasma Infection in Women
1. Pelvic Inflammatory Disease (PID)
The most serious potential complication is Pelvic Inflammatory Disease (PID), an ascending infection that spreads from the vagina and cervix to the uterus, fallopian tubes, and ovaries.
PID can cause permanent structural damage to the female reproductive organs, with potentially irreversible consequences:
- Infertility: due to scarring and occlusion of the fallopian tubes
- Increased risk of ectopic pregnancy: due to tubal damage impairing the normal passage of the fertilized egg
- Chronic pelvic pain: from persistent inflammation and adhesion formation
Signs and symptoms of evolving PID include:
- Pelvic pain, typically bilateral, constant, and often worsening with movement
- General malaise and fatigue
- Pain during intercourse (deep dyspareunia)
- Fever
- Elevated inflammatory markers on blood tests (C-reactive protein (CRP), elevated white blood cell count)
PID requires urgent medical attention and prompt antibiotic treatment to prevent permanent reproductive damage.
2. Complications in Pregnancy
Mycoplasma infection during pregnancy carries specific risks:
- Transmission to the fetus/neonate: M. hominis can be transmitted from mother to baby during delivery, causing neonatal fever at birth and, in severe cases, neonatal sepsis or meningitis
- Spontaneous miscarriage: particularly in early pregnancy
- Preterm birth: due to ascending infection triggering premature contractions
- Chorioamnionitis: infection of the fetal membranes, a serious obstetric emergency
Any pregnant woman with symptoms suggestive of genital Mycoplasma infection should be evaluated and treated promptly.
Complications in Men
- Epididymo-orchitis: infection of the epididymis and testis, potentially affecting fertility
- Prostatitis: Mycoplasma has been implicated in cases of chronic prostatitis
- Male infertility: through direct effects on sperm motility and function
Diagnosis
Accurate diagnosis is essential to differentiate Mycoplasma from other microbiologically and clinically similar infections, and to guide the specific antibiotic therapy required. Misdiagnosis and inappropriate treatment (such as prescribing beta-lactam antibiotics) will lead to treatment failure and risk of progression to complications.
Clinical Evaluation
The gynecologist begins with a thorough clinical assessment:
- Gynecological examination: direct visualization of vaginal discharge, cervical appearance, and assessment of cervical motion tenderness (a key sign of upper genital tract involvement/PID)
- Symptom history: characteristics of discharge, pain, dyspareunia, intermenstrual bleeding
Laboratory and Microbiological Tests
Vaginal Swab (Primary Diagnostic Test)
A vaginal or endocervical swab is the cornerstone of diagnosis. The swab specimen undergoes:
- Culture on selective media: to demonstrate growth of Mycoplasma colonies and confirm infection
- Antibiogram (antimicrobial susceptibility testing): This test is critically important because it identifies which specific antibiotics the isolated strain is susceptible to, guiding targeted treatment. This is particularly relevant for M. genitalium, which has shown increasing antibiotic resistance (particularly to macrolides)
Molecular Testing (PCR: Nucleic Acid Amplification Tests)
PCR-based NAAT (Nucleic Acid Amplification Tests) have become the preferred diagnostic method in many centers, particularly for M. genitalium:
- Significantly more sensitive than culture
- Provides rapid results
- Can simultaneously test for multiple sexually transmitted pathogens
- May include resistance-associated mutation testing (e.g., macrolide resistance detection), which directly guides antibiotic selection
Blood Tests
- Inflammatory markers: C-Reactive Protein (CRP), procalcitonin, and white blood cell count (leukocytes) are elevated in systemic infection or PID.
- Normal inflammatory markers do not exclude localized infection
Pelvic Ultrasound
Indicated when:
- PID is suspected: may reveal thickened fallopian tubes, ovarian abscess (tubo-ovarian abscess), or free pelvic fluid
- Pregnancy with suspected infection: to assess fetal wellbeing and exclude obstetric complications
- Baseline assessment before commencing treatment in complex cases
Treatment and Remedies
Antibiotic Therapy
Antibiotics are the essential therapeutic tool for any bacterial infection. The critical principle in Mycoplasma treatment is:
Beta-lactam antibiotics (penicillins, amoxicillin, amoxicillin-clavulanate, cephalosporins) are completely ineffective against Mycoplasma because the bacterium lacks a cell wall, which is the target of these drugs.
The recommended antibiotic classes for Mycoplasma infection are:
For Mycoplasma Hominis
- Tetracyclines (e.g., doxycycline): first-line treatment; administered for 7–14 days
- Fluoroquinolones (e.g., moxifloxacin, ofloxacin): effective alternative, particularly for PID management
- Clindamycin: active against M. hominis (unlike M. genitalium)
For Mycoplasma Genitalium
Treatment is more complex due to the increasing global prevalence of antibiotic resistance:
- Azithromycin (a macrolide): historically first-line; however, macrolide resistance in M. genitalium is now widespread in many regions (up to 50% or more in some areas)
- Moxifloxacin: currently the most effective agent for macrolide-resistant M. genitalium; reserved for confirmed or suspected resistant cases
- Doxycycline: used as part of combined regimens, though less effective as monotherapy
- Resistance-guided therapy: wherever possible, antibiogram results or molecular resistance testing should guide antibiotic choice
For PID (Multiple Antibiotic Combination Therapy)
PID typically requires combination antibiotic regimens covering multiple potential pathogens (including Chlamydia and gonorrhea in addition to Mycoplasma):
- Doxycycline + metronidazole ± cephalosporin (outpatient mild-moderate PID)
- Intravenous regimens for hospitalized patients with severe PID
Symptomatic Treatment
- Analgesics and anti-inflammatory drugs (NSAIDs): for pain relief, particularly important when PID develops
- Antipyretics: for fever management (paracetamol is generally first-line)
Partner Treatment: Critical Point
Because Mycoplasma is a sexually transmitted infection, both sexual partners must be evaluated and treated simultaneously, regardless of whether the partner has symptoms. Failure to treat the partner leads to inevitable reinfection after the index patient completes treatment.
- Partners should be advised of the diagnosis and strongly encouraged to seek testing and treatment
- Sexual abstinence is recommended until both partners have completed the full antibiotic course and confirmed clearance
Prevention
Since Mycoplasma is transmitted predominantly through sexual contact, prevention focuses on:
1. Barrier Contraception (Condoms)
The consistent and correct use of condoms during all forms of sexual activity (vaginal, oral, anal) is the most effective available measure for reducing transmission risk. While condoms do not provide 100% protection (genital skin contact outside the condom area can still transmit the infection), they significantly reduce risk and should be strongly recommended:
- For all new or casual sexual partners
- When either partner’s STI status is unknown
- As part of a comprehensive sexual health strategy
2. Regular STI Screening
Asymptomatic carriage is common, meaning that routine sexual health screening is an important prevention strategy, even in the absence of symptoms:
- Sexually active individuals with multiple partners should consider annual or more frequent STI testing
- Testing for M. genitalium should be included in comprehensive STI panels, particularly for individuals with symptoms or those identified as contacts of an infected person
3. Genital Hygiene
Appropriate genital hygiene for both partners is important:
- Avoid aggressive douching: disrupts the normal vaginal microbiome and may increase susceptibility to infection
- External washing with mild, pH-appropriate products is sufficient
4. Prompt Treatment of Symptoms
Early recognition and treatment of symptoms prevents ascending infection and the development of PID and its permanent consequences. Any woman experiencing unusual vaginal discharge, dyspareunia, or intermenstrual bleeding should seek prompt medical evaluation.
Sources and Bibliography
- Horner P, Donders G, Cusini M, Gomberg M, Jensen JS, Unemo M. Should we be testing for urogenital Mycoplasma hominis, Ureaplasma parvum and Ureaplasma urealyticum in men and women? A position statement from the European STI Guidelines Editorial Board J Eur Acad Dermatol Venereol. 2018;32(11):1845–1851.
- Jensen JS, Cusini M, Gomberg M, Moi H. 2016 European guideline on Mycoplasma genitalium infections. J Eur Acad Dermatol Venereol. 2016;30(10):1650–1656.
- Lis R, Rowhani-Rahbar A, Manhart LE. Mycoplasma genitalium infection and female reproductive tract disease: a meta-analysis. Clin Infect Dis. 2015;61(3):418–426.
- Taylor-Robinson D, Jensen JS. Mycoplasma genitalium: from Chrysalis to multicolored butterfly. Clin Microbiol Rev. 2011;24(3):498–514.
- Centres for Disease Control and Prevention (CDC). Mycoplasma genitalium: Sexually Transmitted Infections Treatment Guidelines, 2021. https://www.cdc.gov/std/treatment-guidelines/mycoplasma-genitalium.htm
