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
Pricing for Mycoplasma genitalium Testing
- $690 Mycoplasma genitalium DNA single test
- STI DNA screening package (7 items)
- $1,350 HKD, Mycoplasma genitalium & Macrolide resistance test (23S rRNA)
- $1,350 HKD, Mycoplasma genitalium & Fluoroquinolone resistance test (parC)
- $2,300 HKD, Mycoplasma genitalium & Resistance Combo test (23S rRNA + parC)
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:
- Patients with MG DNA positive
- 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 |
⚙️ Testing Protocol & Timeline
Initial Diagnostic Testing
- Test when symptoms present
- Use NAAT on appropriate specimen
Test-of-Cure (TOC)
- Perform 4-6 weeks post-treatment
- Never test with 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% | 12-24 hours | First-line diagnosis |
| Resistance PCR | ＞98% | 12-24 hours | Guiding antibiotic therapy |
| Culture | ＜40% | Weeks | Research only |
| Serology | Unreliable | N/A | Not recommended |
🚨 Key Testing Considerations
Women: Vaginal swabs ＞ urine for highest accuracy
MSM: Multi-site testing (urethral + rectal) essential
📋 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.
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