What is the recommended method for testing Neisseria (N.) gonorrhoeae and Chlamydia (C.) trachomatis in an outpatient setting?

Testing for Neisseria Gonorrhoeae and Chlamydia Trachomatis in the Outpatient Setting

Nucleic acid amplification tests (NAATs) are the recommended method for testing Neisseria gonorrhoeae and Chlamydia trachomatis in the outpatient setting due to their superior sensitivity and specificity compared to other testing methods. 1

Preferred Testing Method

NAAT Testing

• NAATs have higher sensitivity and specificity (>97%) compared to culture and other non-culture tests 1, 2
• Can be performed on multiple specimen types:
  • Urine specimens (first-catch urine)
  • Endocervical swabs
  • Vaginal swabs (clinician or self-collected)
  • Urethral swabs
  • Rectal and pharyngeal swabs (for high-risk individuals)

Specimen Collection Guidelines

For Women:

• Primary specimen site: Endocervical canal 1
• Collection procedure:
  1. Obtain specimens after collecting samples for other tests (Gram stain, Pap smear)
  2. Remove secretions and discharge from cervical os using a sponge or large swab
  3. Insert appropriate swab 1-2 cm into endocervical canal
  4. Rotate swab against wall of canal for 10-30 seconds
  5. Withdraw without touching vaginal surfaces 1
• Alternative: First-catch urine specimen (sensitivity 91-95% compared to endocervical swabs) 2, 3
• Self-collected vaginal swabs are also acceptable in clinical settings 1

For Men:

• Primary specimen site: Urethra or first-catch urine 1
• For urethral specimens:
  1. Collect at least 2 hours after patient has voided
  2. Insert swab 2-4 cm into urethra
  3. Rotate for at least one revolution for 5 seconds
  4. Place in appropriate transport medium 1
• First-catch urine has comparable sensitivity to urethral swabs (84-93%) 2

Special Considerations

Extragenital Testing

• For high-risk individuals, particularly men who have sex with men (MSM), test extragenital sites (rectal, pharyngeal) 4
• Asymptomatic rectal infections are common and would be missed by only testing urogenital sites 4
• While not all NAATs are FDA-cleared for extragenital specimens, many laboratories have validated these tests under CLIA requirements 4

Quality Assurance

• Proper specimen collection is critical for accurate results 1
• Without quality assurance, ≥10% of specimens may be unsatisfactory 1
• Periodic cytologic evaluation of specimen quality is recommended when using non-DFA tests 1

Testing Algorithm

1. Assess risk factors:

   • Age (highest risk: women 20-24 years, followed by 15-19 years) 1
   • Sexual behavior (new partners, multiple partners, inconsistent condom use)
   • Previous STIs
   • Geographic location (gonorrhea is concentrated in specific locations)

2. Select appropriate specimen type based on patient:

   • Women: Endocervical swab (preferred) or first-catch urine
   • Men: First-catch urine or urethral swab
   • For high-risk individuals: Include rectal and/or pharyngeal specimens

3. Use NAAT testing platform:

   • Options include PCR, transcription-mediated amplification (TMA), or strand displacement amplification (SDA)
   • All three methods have high specificity (>97%) 2, 5
   • Sensitivity varies by platform and specimen type

4. Interpret results and follow-up:

   • Positive results require treatment and partner notification 1
   • Consider testing for other STIs in positive patients
   • Retest 3 months after treatment due to high reinfection rates

Common Pitfalls to Avoid

1. Testing only genital sites in high-risk individuals, missing extragenital infections 4
2. Improper specimen collection leading to false-negative results 1
3. Failing to maintain culture capability for suspected treatment failures or cases requiring antimicrobial susceptibility testing 6
4. Not testing asymptomatic individuals who meet screening criteria 1
5. Neglecting partner notification and treatment leading to reinfection 1

Remember that both gonorrhea and chlamydia are reportable infections, so specific diagnosis is important for public health surveillance and partner notification 1.