Trichomoniasis medical therapy

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

Overview

Trichomoniasis can usually be cured with the prescription drug, metronidazole, given by mouth in a single dose. The symptoms of trichomoniasis in infected men may disappear within a few weeks without treatment. However, an infected man, even a man who has never had symptoms or whose symptoms have stopped, can continue to infect or re-infect a female partner until he has been treated. Therefore, both partners should be treated at the same time to eliminate the parasite. Persons being treated for trichomoniasis should avoid sex until they and their sex partners complete treatment and have no symptoms. Metronidazole can be used by pregnant women. Having trichomoniasis once does not protect a person from getting it again. Following successful treatment, people can still be susceptible to re-infection.

Medical Therapy

Pharmacotherapy

• 1. T. vaginalis infection in adults

• Preferred regimen (1): Metronidazole 2 g PO in a single dose
• Preferred regimen (2): Tinidazole 2 g PO in a single dose
• Alternative regimen: Metronidazole 500 mg PO bid for 7 days

• 2. T. vaginalis infection in pregnant and lactating Women

• 2.1 Pregnant women

• Preferred regimen: Metronidazole 2 g PO in a single dose.

• 2.2 Post-partum and Breastfeeding

• Preferred regimen (1): Metronidazole 2 g PO in a single dose.
• Preferred regimen (2): Tinidazole 2 g PO in a single dose
• Note (1): Do not breastfeed for 12-24 hrs following Metronidazole and 72 hrs following Tinidazole
• Note (2): Symptomatic pregnant women, regardless of pregnancy stage, should be tested and considered for treatment. Pregnant women should be advised of the risk and benefits to treatment as infection (definitely) and treatment (possibly)
• Note (3): Pregnant women with HIV who are treated for T. vaginalis infection should be retested 3 months after treatment.

• 3. T. vaginalis infection in patients with HIV

• Preferred regimen: Metronidazole 500 mg PO bid for 7 days

• 4. Persistent or recurrent trichomoniasis

• 4.1 Treatment failure

• Preferred regimen: Metronidazole 500 mg PO bid for 7 days

• 4.2 Treatment failure again

• Preferred regimen (1): Metronidazole 2 g PO for 7 days
• Preferred regimen (2): Tinidazole 2 g PO for 7 days

• 4.3 Nitroimidazole-resistant cases

• Preferred regimen: Tinidazole 2-3 g PO for 14 days

Patients should be advised to avoid consuming alcohol during treatment with metronidazole or tinidazole. Abstinence from alcohol use should continue for 24 hours after completion of metronidazole or 72 hours after completion of tinidazole.

The nitroimidazoles comprise the only class of drugs useful for the oral or parenteral therapy of trichomoniasis. Of these drugs, metronidazole and tinidazole are available in the United States and are cleared by the FDA for the treatment of trichomoniasis. In randomized clinical trials, the recommended metronidazole regimens have resulted in cure rates of approximately 90%–95%, and the recommended tinidazole regimen has resulted in cure rates of approximately 86%–100%. The appropriate treatment of sex partners might increase these reported rates. Randomized controlled trials comparing single 2 g doses of metronidazole and tinidazole suggest that tinidazole is equivalent to, or superior to, metronidazole in achieving parasitologic cure and resolution of symptoms. Treatment of patients and sex partners results in relief of symptoms, microbiologic cure, and reduction of transmission.

Metronidazole gel is considerably less efficacious for the treatment of trichomoniasis (<50%) than oral preparations of metronidazole. Topically applied antimicrobials (e.g., metronidazole gel) are unlikely to achieve therapeutic levels in the urethra or perivaginal glands; therefore, use of the gel is not recommended. Several other topically applied antimicrobials occasionally have been used for treatment of trichomoniasis; however, these preparations probably do not have greater efficacy than metronidazole gel.

Follow-Up

Follow-up is unnecessary for men and women who become asymptomatic after treatment or who are initially asymptomatic. Some strains of T. vaginalis can have diminished susceptibility to metronidazole; however, infections caused by the majority of these organisms respond to tinidazole or higher doses of metronidazole. Low-level metronidazole resistance has been identified in 2%–5% of cases of vaginal trichomoniasis. High-level resistance is rare. Tinidazole has a longer serum half-life and reaches higher levels in genitourinary tissues than metronidazole. In addition, many T. vaginalis isolates have lower minimum inhibitory concentrations (MICs) to tinidazole than metronidazole.

If treatment failure occurs with metronidazole 2 g single dose and reinfection is excluded, the patient can be treated with metronidazole 500 mg orally twice daily for 7 days or tinidazole 2 g single dose. For patients failing either of these regimens, clinicians should consider treatment with tinidazole or metronidazole at 2 g orally for 5 days. If these therapies are not effective, further management should be discussed with a specialist. The consultation should ideally include determination of the susceptibility of T. vaginalis to metronidazole and tinidazole. Consultation and T. vaginalis susceptibility testing is available from CDC.

Special Considerations

Allergy, Intolerance, and Adverse Reactions

Metronidazole and tinidazole are both nitroimidazoles. Patients with an immediate-type allergy to a nitroimidazole can be managed by metronidazole desensitization in consultation with a specialist. Topical therapy with drugs other than nitroimidazoles can be attempted, but cure rates are low (<50%).

Pregnancy

Vaginal trichomoniasis has been associated with adverse pregnancy outcomes, particularly premature rupture of membranes, preterm delivery, and low birth weight. However, data do not suggest that metronidazole treatment results in a reduction in perinatal morbidity. Although some trials suggest the possibility of increased prematurity or low birth weight after metronidazole treatment, limitations of the studies prevent definitive conclusions regarding risks of treatment . Treatment of T. vaginalis might relieve symptoms of vaginal discharge in pregnant women and might prevent respiratory or genital infection of the newborn and further sexual transmission. Clinicians should counsel patients regarding the potential risks and benefits of treatment. Some specialists would defer therapy in asymptomatic pregnant women until after 37 weeks’ gestation. In addition, these pregnant women should be provided careful counseling regarding condom use and the continued risk of sexual transmission.

Women may be treated with 2 g of metronidazole in a single dose. Metronidazole is pregnancy category B (animal studies have revealed no evidence of harm to the fetus, but no adequate, well-controlled studies among pregnant women have been conducted). Multiple studies and meta-analyses have not demonstrated a consistent association between metronidazole use during pregnancy and teratogenic or mutagenic effects in infants. Tinidazole is pregnancy category C (animal studies have demonstrated an adverse event, and no adequate, well-controlled studies in pregnant women have been conducted), and its safety in pregnant women has not been well-evaluated.

In lactating women who are administered metronidazole, withholding breastfeeding during treatment and for 12–24 hours after the last dose will reduce the exposure of metronidazole to the infant. While using tinidazole, interruption of breastfeeding is recommended during treatment and for 3 days after the last dose.

HIV Infection

Patients who have trichomoniasis and also are infected with HIV should receive the same treatment regimen as those who are HIV negative. The incidence, persistence, and recurrence of trichomoniasis in HIV-infected women are not correlated with immune status.