Treatment of Trichomoniasis in Adult Females
For an adult female with trichomoniasis and a history of unprotected sexual activity, treat with metronidazole 500 mg orally twice daily for 7 days, and simultaneously treat all sexual partners with the same regimen to prevent reinfection. 1, 2
Primary Treatment Regimen
Metronidazole 500 mg orally twice daily for 7 days is the preferred regimen for women, as recent evidence demonstrates this multidose regimen reduces treatment failure rates compared to single-dose therapy (2% failure vs higher rates with single-dose at 1-month follow-up). 2
An alternative single-dose regimen of metronidazole 2 g orally may be used when medication adherence is a major concern, though it has slightly lower efficacy in women. 3, 1, 4
Both regimens should be taken with food to minimize gastrointestinal side effects. 1, 5
Cure rates with metronidazole therapy range from 90-95% when partners are treated concurrently. 3, 2
Critical Partner Management
All sexual partners must be treated simultaneously with the same regimen, regardless of symptom status, as failure to treat partners is the most common cause of apparent treatment failure due to reinfection. 3, 1, 5
The patient must abstain from sexual intercourse until both she and all partners complete treatment and are asymptomatic. 3, 1, 6
Male partners are often asymptomatic carriers who serve as reservoirs for reinfection. 5
Important Treatment Considerations
Never use topical metronidazole gel for trichomoniasis - it has less than 50% efficacy because it cannot achieve therapeutic drug levels in the urethra or perivaginal glands where the organism persists. 3, 5
Advise the patient to avoid alcohol during treatment and for at least 24-72 hours after completion due to disulfiram-like reaction (nausea, vomiting, flushing, headache, abdominal cramps). 5, 6
Tinidazole 2 g orally as a single dose is an FDA-approved alternative with similar efficacy to metronidazole. 7
Management of Treatment Failure
For first treatment failure: Re-treat with metronidazole 500 mg twice daily for 7 days (if single-dose was used initially) or consider partner reinfection. 3, 1, 5
For second treatment failure: Administer metronidazole 2 g once daily for 3-5 days. 3, 1, 5
For persistent failure after high-dose therapy: Consult an infectious disease specialist and consider susceptibility testing, as approximately 4-5% of T. vaginalis strains demonstrate metronidazole resistance. 3, 1, 8
Follow-Up and Rescreening
Routine follow-up is unnecessary for patients who become asymptomatic after treatment. 3, 1, 5
Rescreen at 3 months after treatment completion due to high rates of reinfection (repeat infections are common in women with untreated or inadequately treated partners). 1, 2
If severe cervical inflammation was present initially, repeat Pap smear 3 months after treatment, as T. vaginalis can interfere with accurate cytological assessment. 1, 4
Clinical Significance
T. vaginalis infection increases risk of HIV acquisition and transmission, making treatment particularly important in this patient with unprotected sexual activity. 1, 2, 9
The infection is associated with adverse pregnancy outcomes including preterm birth, premature rupture of membranes, and low birthweight. 1, 2, 9
Common Pitfalls to Avoid
Failing to treat sexual partners simultaneously - this is the primary cause of apparent treatment failure and perpetuates transmission. 1, 5
Using inadequate treatment duration in women - single-dose therapy has higher failure rates in females compared to the 7-day regimen. 2
Assuming asymptomatic partners don't need treatment - male partners are frequently asymptomatic carriers. 5, 4