What is the diagnostic and treatment process for a throat swab positive for Sexually Transmitted Diseases (STDs) such as gonorrhea or chlamydia?

Throat Swab for STDs: Diagnostic and Treatment Approach

Diagnostic Testing for Pharyngeal STIs

Culture is the most widely available and recommended diagnostic method for detecting gonorrhea and chlamydia in the pharynx, as nucleic acid amplification tests (NAATs) are not FDA-cleared for pharyngeal specimens and may cross-react with commensal Neisseria species commonly found in the throat. 1

Key Diagnostic Considerations

• Gram stain is insufficient for pharyngeal specimens and should not be used for diagnosis, as it lacks adequate sensitivity and specificity for detecting infection at this site 1

• NAATs have limitations for pharyngeal testing: while some laboratories have validated NAATs for pharyngeal swabs after meeting CLIA requirements, these tests can cross-react with nongonococcal Neisseria and related organisms naturally present in the throat 1

• Culture remains the gold standard for pharyngeal gonorrhea detection, providing both diagnosis and antimicrobial susceptibility testing when needed 1

• Self-collected oropharyngeal swabs are acceptable and well-tolerated by patients, with over 75% reporting the collection as "easy" or "very easy" 2

Comprehensive STI Screening

All patients tested for pharyngeal gonorrhea or chlamydia must be tested for other STIs, including genital gonorrhea, chlamydia, syphilis, and HIV. 1

Multi-Site Testing Requirements

• Sexual history determines testing sites: assess specific sexual practices to identify all anatomical sites requiring testing (genital, rectal, pharyngeal) 3, 4

• Men who have sex with men (MSM) require pharyngeal and rectal testing based on sexual practices, as extragenital infections are common in this population 3

• Approximately 53-100% of extragenital gonorrhea and chlamydia infections are asymptomatic, making screening essential even without symptoms 5

Treatment for Positive Pharyngeal Gonorrhea

For uncomplicated pharyngeal gonorrhea, treat with ceftriaxone 500 mg intramuscularly as a single dose for patients weighing less than 150 kg (331 lbs). 6, 7, 8

Treatment Protocol

• Dual therapy for chlamydia co-infection: if chlamydia test results are unavailable or if using a non-NAAT test that was negative, treat empirically for both infections 1, 4

• Preferred chlamydia treatment: doxycycline 100 mg orally twice daily for 7 days 1, 9, 6, 7, 8

• Alternative chlamydia treatment: azithromycin 1 g orally as a single dose, though doxycycline is preferred 1, 10, 6

• Avoid quinolones: do not use fluoroquinolones (ciprofloxacin, ofloxacin) for gonorrhea treatment without confirmed susceptibility due to widespread resistance 1, 4

Critical Treatment Considerations

• Test of cure is mandatory for all pharyngeal gonorrhea cases due to higher treatment failure rates at this anatomic site 7

• Culture with susceptibility testing should be performed if infection persists after treatment, as nonculture tests cannot provide antimicrobial resistance information 1

• Patients should abstain from sexual activity for 7 days after single-dose therapy or until completion of 7-day regimens and resolution of symptoms 1

Partner Management and Follow-Up

All sexual partners from the preceding 60 days must be evaluated, tested, and treated empirically for both gonorrhea and chlamydia. 1, 4

Follow-Up Testing Requirements

• Retest at 3 months: all patients diagnosed with gonorrhea or chlamydia should be retested approximately 3 months after treatment due to high reinfection rates (regardless of whether partners were treated) 1, 4, 6

• Test of cure at 4 weeks: pregnant patients require test of cure 4 weeks after treatment completion 6

• Partners should abstain from sexual intercourse until both patient and all partners have completed treatment and are asymptomatic 4

Common Pitfalls to Avoid

• Do not rely on NAATs alone for pharyngeal specimens without laboratory validation, as false positives from cross-reactivity with commensal organisms can occur 1

• Do not skip multi-site testing: pharyngeal infection often coexists with genital or rectal infection, and testing only one site misses the majority of infections 3, 5

• Do not use quinolones empirically: resistance is widespread, particularly among MSM (23.9% resistance rate) 1

• Do not omit test of cure for pharyngeal gonorrhea, as this site has higher treatment failure rates than genital infections 7

• Do not forget HIV/syphilis screening: all patients with any STI diagnosis require testing for other STIs including HIV and syphilis 1