How is oral chlamydia (Chlamydia trachomatis) and gonorrhea diagnosed?

Diagnosis of Oral Chlamydia and Gonorrhea

Oral chlamydia and gonorrhea are diagnosed using nucleic acid amplification tests (NAATs) on pharyngeal swab specimens, with provider-collected or self-collected pharyngeal swabs being the standard method of specimen collection.

Specimen Collection Methods

Provider-Collected Specimens

• Provider-collected pharyngeal swabs involve swabbing the posterior pharynx and tonsillar areas 1
• These have traditionally been the standard collection method for diagnosing oral STIs

Self-Collected Specimens

• Self-collected pharyngeal swabs have shown comparable accuracy to provider-collected specimens 1
• Studies show high agreement (99.4%) between self-collected and clinician-collected pharyngeal swabs 1
• Self-collection is highly acceptable to patients, with 92% willing to self-collect at home 1

Alternative Collection Methods

• Oral rinse specimens (using mouthwash or water) have shown promise:
  • Mouthwash: 72% sensitivity, 99.1% specificity for gonorrhea
  • Water rinse: 82% sensitivity, 99.7% specificity for gonorrhea 2
• These methods are less invasive and more acceptable to patients but currently have lower sensitivity than direct swabs

Testing Technology

Recommended Testing Methods

• NAATs are the gold standard for detecting both Chlamydia trachomatis and Neisseria gonorrhoeae 3
• NAATs offer superior sensitivity and specificity compared to culture and other testing methods 3, 4
• Common NAAT platforms include:
  • PCR (polymerase chain reaction)
  • TMA (transcription-mediated amplification)
  • SDA (strand displacement amplification) 3

Important Considerations

• Most NAATs are not FDA-cleared for pharyngeal specimens, though many laboratories have validated these tests for such use 1
• Some laboratories have established performance standards to meet CLIA requirements for pharyngeal testing 1
• Specificity for pharyngeal specimens is typically >99.5%, though sensitivity may vary by platform 5

Clinical Approach to Testing

Who Should Be Tested

• Testing should be guided by sexual risk assessment
• Men who have sex with men (MSM) should be routinely tested at extragenital sites including the pharynx 3
• Anyone reporting oral sexual contact with a partner who has a known STI
• Individuals with symptoms (though most oral infections are asymptomatic) 6

Testing Pitfalls to Avoid

1. Missing asymptomatic infections: 81-98% of infections would be missed if relying on symptoms alone 6
2. Testing only genital sites: Extragenital infections are common and would be missed by only testing urogenital sites 3
3. Improper specimen collection: Can lead to false-negative results 3
4. Failing to test all exposed sites: Comprehensive testing should include all sites of potential exposure

Follow-up and Management

• Patients with positive results should be treated according to current guidelines
• Partner notification and treatment is essential to prevent reinfection 3
• Consider testing for other STIs in patients with positive results
• Retest 3 months after treatment due to high reinfection rates 3

Advantages of NAATs for Oral STI Testing

• Higher sensitivity compared to culture
• Ability to use less invasive collection methods
• Potential for self-collection, increasing testing accessibility
• Faster turnaround time for results 4

By using NAATs with appropriate specimen collection techniques, clinicians can effectively diagnose oral chlamydia and gonorrhea infections, even when asymptomatic, leading to proper treatment and prevention of transmission.