What is the treatment for Trichomonas (trichomo) vaginalis infection?

Treatment of Trichomoniasis

For Trichomonas vaginalis infection, treat with metronidazole 500 mg orally twice daily for 7 days as the preferred regimen, and simultaneously treat all sexual partners to prevent reinfection. 1, 2

First-Line Treatment Regimen

Metronidazole 500 mg orally twice daily for 7 days is the preferred treatment with cure rates of approximately 90-95%. 1, 2 This multi-dose regimen is superior to single-dose therapy because:

• Trichomonas can persist in the urethra and perivaginal glands, requiring sustained therapeutic drug levels 1
• A randomized controlled trial in HIV-uninfected women demonstrated that the 7-day regimen reduced the proportion of women with persistent infection at 1-month test of cure compared with single-dose therapy 2

Alternative Regimen (When Adherence Is a Concern)

Metronidazole 2 g orally as a single dose may be used when medication adherence is a major concern. 3, 1 This regimen achieves approximately 95% cure rates in clinical trials but is less effective than the 7-day course. 3 The single-dose regimen remains the preferred treatment specifically in men. 2

Tinidazole 2 g orally as a single dose is an FDA-approved alternative nitroimidazole with similar efficacy. 4

Critical Management Requirements

Simultaneous Partner Treatment (Non-Negotiable)

• All sexual partners must be treated simultaneously regardless of symptom status to prevent reinfection. 3, 5, 1
• Male partners often have asymptomatic urethral infection (80% of men are asymptomatic) that serves as a reservoir for reinfection. 6, 1
• Patients must abstain from sexual activity until both partners complete treatment and are asymptomatic. 5, 1
• Reinfection is extremely common when partners are not treated simultaneously. 5

Important Pitfall to Avoid

Never use topical metronidazole gel for trichomoniasis - efficacy is less than 50% because it cannot achieve therapeutic levels in the urethra or perivaginal glands. 3, 1 Metronidazole gel is approved only for bacterial vaginosis, not trichomoniasis. 3

Treatment Failure Algorithm

If treatment fails, follow this stepwise approach:

1. First treatment failure: Re-treat with metronidazole 500 mg twice daily for 7 days 3, 1
2. Repeated treatment failure: Administer metronidazole 2 g once daily for 3-5 days 3, 1
3. Persistent failure after above regimens: Consult an expert and obtain susceptibility testing of T. vaginalis isolate 3

Antimicrobial resistance to 5-nitroimidazole remains low (4.3%) but is an emerging concern. 2

Special Populations

Pregnancy

• Pregnant women can be treated with metronidazole 2 g orally as a single dose after the first trimester. 1, 7
• Treatment is important because trichomoniasis is associated with premature rupture of membranes, preterm delivery, and low birthweight. 5, 6, 1
• During the first trimester, treatment decisions should weigh risks versus benefits, though metronidazole is generally considered safe. 7

HIV Infection

• Use the same treatment regimen as for HIV-negative patients, but consider the 7-day regimen preferentially. 3, 1, 8
• Trichomoniasis increases the risk of HIV transmission and acquisition. 5, 6

Metronidazole Allergy

• Desensitization may be required as effective alternatives are extremely limited. 1
• Tinidazole may be attempted if there is no cross-reactivity. 4

Patient Counseling

Patients must avoid alcohol during treatment and for at least 24 hours after completion due to disulfiram-like reaction causing nausea, vomiting, flushing, headache, and abdominal cramps. 1

Follow-Up

• Routine follow-up is unnecessary for patients who become asymptomatic after treatment. 3, 1
• Rescreening at 3 months after treatment is recommended due to high rates of repeat and persistent infections. 2
• Repeat infections are common in women, particularly when partners are not treated. 2

Why This Matters Clinically

Beyond causing symptomatic vaginitis and urethritis, trichomoniasis has serious health consequences:

• Facilitates HIV transmission and acquisition 5, 6
• Associated with pelvic inflammatory disease in some cases 6
• Causes adverse pregnancy outcomes including premature rupture of membranes, preterm delivery, and low birthweight 5, 6
• May facilitate transmission of other sexually transmitted infections 6
• Can cause urethritis, epididymitis, and prostatitis in men when symptomatic 6