Mycoplasma genitalium Testing: Precision Diagnosis for a Stealth STI
Accurate detection of Mycoplasma genitalium (MG) requires specialized testing due to its unculturable nature and non-specific symptoms. Modern diagnostics combine NAAT technology with resistance screening for effective management.
🔬 Recommended Testing Methods
1. NAAT (Nucleic Acid Amplification Test)
Gold standard for diagnosis (＞95% sensitivity)
- Sample Types:
- Men: First-void urine (≥20ml, first part of stream)
- Women: Vaginal swab (patient-collected or clinician-collected)
- MSM/rectal symptoms: Anal swab
- Results in 24-48 hours
- Detects active infection through bacterial DNA/RNA
2. Antimicrobial Resistance (AMR) Testing
Critical due to global resistance crisis
- Tests for mutations in:
- 23S rRNA gene (macrolide resistance)
gyrA/parC genes (fluoroquinolone resistance)
Recommended for:
- All treatment failures
- Patients in high-resistance regions (Asia/Pacific: 60-80% macrolide resistance)
- MSM populations
🎯 Who Should Be Tested?
| Clinical Scenario | Testing Recommendation |
|---|---|
| Symptomatic men | Urethritis (discharge/dysuria) after ruling out chlamydia/gonorrhea |
| Symptomatic women | Cervicitis (abnormal bleeding), PID, or persistent vaginal discharge |
| Sexual partners | All partners within 3 months of MG diagnosis |
| Infertility workup | Both partners with unexplained infertility |
| Treatment failure | Persistent symptoms post-antibiotic therapy |
| Asymptomatic screening | Not routinely recommended (risk of overtreatment) |
⚙️ Testing Protocol & Timeline
Initial Diagnostic Testing
- Test when symptoms present
- Use NAAT on appropriate specimen
Test-of-Cure (TOC)
- Perform 21-28 days post-treatment
- Never test 3 weeks (false positives from dead bacteria)
Resistance Testing
- Required before second-line treatment
📌 Critical: 40% of MSM have rectal MG – test urethral AND rectal sites
⚖️ Test Comparison Table
| Method | Accuracy | Turnaround | Clinical Use |
|---|---|---|---|
| NAAT | 95-99% | 1-3 days | First-line diagnosis |
| Resistance PCR | ＞98% | 3-7 days | Guiding antibiotic therapy |
| Culture | ＜40% | Weeks | Research only |
| Serology | Unreliable | N/A | Not recommended |
🚨 Key Testing Considerations
Women: Vaginal swabs ＞ endocervical ＞ urine for highest accuracy
MSM: Multi-site testing (urethral + rectal) essential
Specimen Handling:
- Room temp: Stable ≤5 days
- Refrigerated: ≤30 days
- Frozen: Long-term storage
Treatment Implications:
- Macrolide resistance → Use doxycycline + moxifloxacin
- Dual resistance → Pristinamycin (special access)
📋 When to Suspect MG Infection
✔️ Persistent urethritis/cervicitis after standard STI treatment
✔️ Recurrent PID without identified cause
✔️ Partner diagnosed with MG
✔️ Unexplained infertility in couples
Red Flag: 80% of MG-positive men with urethritis have failed previous chlamydia treatment
💡 Essential Testing Principles
NAAT is mandatory – culture and serology are invalid
Resistance-guided therapy prevents treatment failures
Partner testing breaks reinfection cycles
Test-of-cure confirms eradication (especially with resistant strains)
Confirm clearance 4 weeks post-treatment before resuming unprotected sex.
(Text Only)
