What is the recommended treatment for a patient diagnosed with Trichomonas (a sexually transmitted infection)?

Treatment of Trichomonas Vaginalis Infection

For women, treat with metronidazole 500 mg orally twice daily for 7 days; for men, use metronidazole 2 g orally as a single dose. 1

First-Line Treatment Regimens

For Women

• Metronidazole 500 mg orally twice daily for 7 days is the preferred regimen, as a 2022 randomized controlled trial demonstrated this multidose regimen significantly reduced treatment failure at 1-month test of cure compared to single-dose therapy in HIV-uninfected women. 1
• The 7-day regimen achieves sustained therapeutic drug levels in the urethra and perivaginal glands where Trichomonas persists, which is critical for cure. 2
• This regimen achieves approximately 90-95% cure rates. 3, 4

For Men

• Metronidazole 2 g orally as a single dose remains the preferred treatment. 1
• The single-dose regimen is effective in men and improves adherence. 3, 5

Alternative Single-Dose Option

• Metronidazole 2 g orally as a single dose may be used in women when medication adherence is a major concern, though it has higher failure rates than the 7-day regimen. 3, 4, 2
• Tinidazole 2 g orally as a single dose is an FDA-approved alternative with similar efficacy to metronidazole. 6

Critical Administration Instructions

• Take all doses with food to minimize gastrointestinal side effects. 3, 6
• Avoid alcohol during treatment and for 24 hours after metronidazole (or 3 days after tinidazole) due to disulfiram-like reaction causing severe nausea, vomiting, flushing, and abdominal cramps. 2, 6

Mandatory Partner Management

All sexual partners must be treated simultaneously with the same regimen, regardless of symptoms or test results. 3, 4, 7

• Most men infected with T. vaginalis are asymptomatic, making them efficient vectors for reinfection. 7
• Up to 50% of infected women may also be asymptomatic. 7
• Patients must abstain from sexual activity until both they and all partners complete treatment and are asymptomatic. 3, 4, 2
• Failure to treat partners is the most common cause of apparent treatment failure due to reinfection. 4, 7

Management of Treatment Failure

First Treatment Failure

• Re-treat with metronidazole 500 mg orally twice daily for 7 days. 3, 4, 2

Second Treatment Failure

• Administer metronidazole 2 g orally once daily for 3-5 days. 3, 4, 2

Persistent Treatment Failure

• Consult an infectious disease specialist for susceptibility testing of T. vaginalis to metronidazole. 3, 4
• Metronidazole resistance occurs in approximately 4-5% of cases and is an emerging concern. 4, 8, 1
• CDC consultation is available at 770-488-4115. 3

Special Populations

Pregnancy

• Pregnant women should be treated with metronidazole 2 g orally as a single dose after the first trimester. 3, 2
• Treatment is important because trichomoniasis is associated with premature rupture of membranes, preterm delivery, and low birth weight. 3, 7, 2
• Multiple studies and meta-analyses have not demonstrated teratogenic or mutagenic effects in infants from metronidazole use during pregnancy. 3
• Symptomatic pregnant women should be treated to ameliorate symptoms. 3

HIV-Infected Patients

• Use the same treatment regimens as for HIV-negative patients. 3, 2
• Trichomoniasis increases the risk of HIV acquisition and transmission. 4, 1, 9

Metronidazole Allergy

• Patients with immediate-type allergy to metronidazole can be managed by desensitization, as effective alternatives are extremely limited. 3, 2
• Topical therapies with non-nitroimidazole drugs have cure rates below 50% and are not recommended. 3

Follow-Up and Rescreening

• Routine follow-up is unnecessary for patients who become asymptomatic after treatment. 3, 2
• Rescreen all women at 3 months after treatment completion, as repeat and persistent infections are common. 1
• If severe inflammation was present, repeat Pap smear should be performed 3 months after treatment, as T. vaginalis can interfere with accurate cytological assessment. 4, 5

Critical Pitfalls to Avoid

Never Use Topical Metronidazole

• Metronidazole gel has less than 50% efficacy against T. vaginalis and is not recommended. 3, 4, 2
• Topical preparations cannot achieve therapeutic levels in the urethra or perivaginal glands where the organism persists. 3, 2

Ensure Partner Treatment

• Failure to treat sexual partners is the primary cause of reinfection and apparent treatment failure. 4, 7
• Male partners often have asymptomatic urethral infection that serves as a reservoir for reinfection. 2

Consider Screening Before Procedures

• Screen and treat women for trichomoniasis before any reproductive tract surgery (hysterectomy, cesarean section, therapeutic abortion) to prevent postoperative infections. 10

Clinical Significance

Trichomoniasis has serious health consequences beyond genital symptoms, including facilitation of HIV transmission and acquisition, adverse pregnancy outcomes, and potential association with cervical cancer. 4, 7, 1, 9