When is a test of cure recommended after treatment for trichomoniasis?

Test of Cure for Trichomonas Infection

Follow-up testing for trichomonas (test of cure) is not recommended for men and women who become asymptomatic after treatment or who are initially asymptomatic. 1

Standard Recommendations

The CDC guidelines clearly state that routine test of cure is unnecessary for most patients treated for trichomoniasis. This recommendation is based on the high efficacy of metronidazole treatment regimens, which have cure rates of approximately 90-95% when taken as directed 1.

Exceptions Requiring Test of Cure

While routine testing is not needed for most patients, there are specific situations where test of cure should be performed:

1. Treatment Failure:

   • If symptoms persist after initial treatment
   • If reinfection is suspected
   • In these cases, patients should be retreated with metronidazole 500 mg twice daily for 7 days 1

2. Pharyngeal Gonorrhea with Alternative Treatment:

   • Although not directly related to trichomonas, it's worth noting that patients with pharyngeal gonorrhea who receive alternative treatment regimens should have a test of cure 14 days after treatment 1

3. Optimal Timing for Test of Cure (when needed):

   • For patients who received multidose metronidazole (500 mg twice daily for 7 days): Test of cure should be performed at 3 weeks after completion of treatment 2
   • For patients who received single-dose metronidazole (2 g once): Test of cure should be performed at 4 weeks after treatment 2

Special Considerations

Pregnancy

• Pregnant women should not be treated during the first trimester 3
• For pregnant women requiring treatment after the first trimester, the 7-day course is preferred over single-dose therapy 3
• When repeat courses are required, an interval of 4-6 weeks should elapse between courses, and the presence of trichomonas should be reconfirmed by appropriate laboratory measures 3

Persistent Infections

• If treatment failure occurs repeatedly after the 7-day regimen, the patient should be treated with a single 2-g dose of metronidazole once daily for 3-5 days 1
• Patients with laboratory-documented infection who do not respond to the 3-5 day treatment regimen and who have not been reinfected should be managed in consultation with a specialist 1

Rescreening vs. Test of Cure

It's important to distinguish between test of cure (to confirm treatment success) and rescreening (to detect reinfection):

• Test of cure: Not routinely recommended except in specific situations noted above
• Rescreening: Recommended at 3 months after treatment for women, especially HIV-infected women, due to high rates of reinfection 1, 4

Testing Methods

When testing is necessary, the following methods can be used:

• Culture (most sensitive commercially available method) 1
• Nucleic acid amplification tests (NAATs) - highly sensitive but may detect non-viable organisms if performed too soon after treatment 2
• Microscopy of vaginal secretions (wet mount) - less sensitive (60-70%) 1

Key Pitfalls to Avoid

1. Testing too soon after treatment: May detect remnant nucleic acid from non-viable organisms, falsely classifying patients as still infected 2

2. Failing to distinguish between treatment failure and reinfection: Ensure partners have been treated to prevent reinfection 1

3. Not considering resistant strains: Some T. vaginalis strains have diminished susceptibility to metronidazole, requiring higher doses for effective treatment 1

4. Confusing test of cure with rescreening: Test of cure is to confirm treatment success, while rescreening at 3 months is to detect reinfection 1, 4