What is the recommended diagnostic test and treatment for a sexually active adult with suspected Trichomonas vaginalis infection and a history of high-risk sexual behavior?

Diagnostic Testing for Trichomonas Vaginalis

For sexually active adults with suspected trichomoniasis and high-risk sexual behavior, nucleic acid amplification testing (NAAT) is the recommended diagnostic test, as it offers superior sensitivity compared to all other methods and can be performed on multiple specimen types including vaginal swabs, urine, and endocervical specimens. 1, 2

Recommended Diagnostic Approach

First-Line Testing: NAAT

• NAAT is the preferred diagnostic method when available, providing the highest sensitivity and not requiring viable organisms for detection 2
• For women, NAAT is FDA-cleared and accepts vaginal swabs, endocervical swabs, urine, and liquid-based cytology specimens 1, 2
• Specimens remain stable at room temperature for 7 days, allowing flexibility in transport 2
• NAAT demonstrates superior sensitivity compared to wet mount (40-80% sensitivity) and culture (approximately 70% sensitivity) 1, 3, 2

Alternative Testing Methods (When NAAT Unavailable)

• Culture in Diamond media or InPouch TV system has approximately 70% sensitivity compared to NAAT but is not widely available 1, 2
• Point-of-care antigen detection tests (OSOM Trichomonas Rapid Test) have sensitivity ranging from 62-95% compared to culture and NAAT 2
• Nucleic acid probe test (Affirm VPIII) detects T. vaginalis but has lower sensitivity than NAAT 1, 2

Critical Diagnostic Pitfalls to Avoid

• Never rely solely on wet mount microscopy due to poor sensitivity of 40-80%; a negative wet mount does not exclude trichomoniasis 1, 2
• Wet mount requires immediate viewing within 30 minutes to 2 hours of collection, as organisms lose motility and become undetectable 2
• Do not use routine Papanicolaou test to diagnose T. vaginalis infection due to poor sensitivity and specificity 1

Clinical Context for Testing

Who Should Be Tested

• All HIV-infected women should be screened annually for T. vaginalis 1
• Consider screening in women at high risk: those with new or multiple partners, history of STIs, or who exchange sex for payment or inject drugs 1
• Test any woman with vaginal discharge, especially when vaginal pH is >4.5 2
• Up to 50% of infections are asymptomatic, so absence of symptoms does not exclude infection 2

Testing in Males

• NAAT has demonstrated superior sensitivity for trichomonas diagnosis in men, but is not FDA-licensed for male specimens 1, 3
• Laboratories that have met CLIA requirements and validated their T. vaginalis NAAT performance on male specimens may perform this test 1
• Approximately 80% of male infections are asymptomatic, creating a substantial reservoir for ongoing transmission 3

Treatment Considerations

FDA-Approved Regimens

• Metronidazole 2g orally as a single dose or 500mg twice daily for 7 days 4, 5
• Tinidazole 2g orally as a single dose is an alternative 6, 5
• Nitroimidazoles (metronidazole and tinidazole) are the mainstay of therapy 5

Essential Treatment Principles

• Partners of infected patients must be treated simultaneously to prevent reinfection, even without screening 7, 6, 4
• This is critical because trichomoniasis is a sexually transmitted disease with potentially serious sequelae 6
• Rescreening at 3 months after treatment should be considered, especially for HIV-infected women 1

Clinical Significance in High-Risk Populations

• T. vaginalis infection has been associated with vaginitis, PID, preterm labor, and increased HIV transmission 1
• Substantial racial disparity exists, with prevalence rates 10 times higher among non-Hispanic African Americans compared to non-Hispanic white and Mexican American populations 1, 3
• In males, T. vaginalis can cause urethritis, epididymitis, and prostatitis 1, 3