Mycoplasma genitalium and Unilateral Testicular Pain
Mycoplasma genitalium does not typically cause constant unilateral testicular pain; when it does cause testicular symptoms, they are more commonly associated with epididymitis presenting as testicular swelling or inflammation rather than isolated constant pain.
Clinical Presentation of M. genitalium
M. genitalium primarily manifests as urethritis in men, not as isolated testicular pain. The typical symptoms include:
- Urethral discharge (most common)
- Dysuria (painful urination) 1, 2
- Testicular swelling or inflammation when epididymitis develops 1
Research demonstrates that testicular involvement occurs but is not the primary presentation. In a study of symptomatic men, M. genitalium infection was associated with testis inflammation and pelvic pain, but these occurred alongside urethral symptoms 1. The 2024 EAU guidelines clearly identify the predominant pathogens in acute epididymitis as Enterobacterales, C. trachomatis, and N. gonorrhoeae—notably not listing M. genitalium as a primary cause 3.
Key Clinical Distinctions
Acute vs. Chronic Presentation:
- Most M. genitalium infections present acutely (75.6% in recent data) with urethral symptoms 2
- Chronic symptoms are associated with previous antibiotic use and history of STIs 2
- Isolated constant unilateral testicular pain without urethral symptoms is atypical for M. genitalium
Important Caveats
When to consider M. genitalium in testicular pain:
- If accompanied by urethral discharge or dysuria
- In cases of persistent urethritis that has progressed to epididymitis
- When standard epididymitis pathogens have been ruled out
- In sexually active men with risk factors for STIs
What constant unilateral testicular pain more likely suggests:
- Classic bacterial epididymitis (E. coli, other Enterobacterales)
- Chlamydia or gonorrhea-related epididymitis
- Testicular torsion (surgical emergency—pain is severe and acute)
- Chronic orchialgia/chronic pelvic pain syndrome 4
- Testicular mass or other structural pathology
Diagnostic Approach
If M. genitalium is suspected in a patient with testicular symptoms:
- Look for accompanying urethral symptoms (discharge, dysuria)
- Test for M. genitalium only in persistent urethritis, cervicitis, or when indicated by CDC guidelines 5
- Do not test asymptomatic patients without MG exposure history 5
- Consider co-infections: 39.3% have concurrent C. trachomatis and 21.3% have N. gonorrhoeae 2
The bottom line: Isolated constant unilateral testicular pain is not a characteristic presentation of M. genitalium infection. If testicular pain exists with M. genitalium, it typically occurs as part of epididymitis with concurrent urethral symptoms, not as an isolated finding.