Mycoplasma and Green Penile Discharge
Mycoplasma genitalium does NOT typically cause green penile discharge—green discharge is most characteristic of gonorrhea (Neisseria gonorrhoeae), while Mycoplasma genitalium causes mucopurulent (white to yellow) discharge similar to chlamydia. 1
Understanding Discharge Color and Etiology
Green Discharge Indicates Gonorrhea
- Green or profusely purulent discharge strongly suggests gonococcal urethritis, which is caused by N. gonorrhoeae, not Mycoplasma 1
- The CDC guidelines specifically describe gonococcal infection as producing purulent discharge with Gram-negative intracellular diplococci on urethral smear 1
Mycoplasma Genitalium Causes Mucopurulent Discharge
- Mycoplasma genitalium is an established cause of nongonococcal urethritis (NGU), producing mucopurulent (not green) discharge 1
- The CDC recognizes M. genitalium as causing 15-25% of NGU cases, presenting with mucopurulent material, dysuria, or urethral pruritis 1
- Research confirms that M. genitalium causes a clinical syndrome similar to chlamydia but distinct from gonorrhea, with less severe discharge that is not characteristically green 2
Clinical Approach to Penile Discharge
Immediate Diagnostic Steps
- Perform Gram stain of urethral secretions: This is the preferred rapid diagnostic test with high sensitivity and specificity 1
- Presence of Gram-negative intracellular diplococci = gonorrhea (likely green discharge)
- Absence of diplococci with >5 WBCs per oil immersion field = NGU (possibly Mycoplasma)
- Order nucleic acid amplification tests (NAATs) for N. gonorrhoeae, C. trachomatis, and M. genitalium if available 1
Treatment Based on Discharge Characteristics
- If green/profusely purulent discharge is present: Treat empirically for gonorrhea AND chlamydia while awaiting test results 1
- If mucopurulent (white/yellow) discharge: Consider NGU pathogens including Mycoplasma genitalium 1
- Azithromycin is more effective than doxycycline for M. genitalium, while moxifloxacin is needed for azithromycin-resistant cases 3, 4
Critical Pitfalls to Avoid
- Do not assume all penile discharge is the same: Color and consistency provide crucial diagnostic clues about the causative organism 1
- Do not overlook co-infections: Multiple pathogens (gonorrhea + chlamydia, gonorrhea + Trichomonas) commonly occur together 2
- Do not delay treatment in high-risk patients: If diagnostic tools are unavailable, treat empirically for both gonorrhea and chlamydia 1
- Remember that Mycoplasma testing is not widely available: Most laboratories do not offer FDA-cleared M. genitalium assays, requiring in-house validation 1