From the Guidelines
Trichomonas vaginalis infection should be treated with oral metronidazole 500 mg twice daily for 7 days or a single 2-gram dose, as this regimen has resulted in cure rates of approximately 90%-95% 1.
Diagnosis and Treatment
Trichomonas vaginalis is a sexually transmitted parasite that causes trichomoniasis, a common infection affecting both men and women.
- Symptoms in women include frothy, yellow-green vaginal discharge with itching and irritation, while men are often asymptomatic but can experience urethral discharge or irritation.
- The infection is diagnosed through microscopic examination of vaginal secretions or urine samples, with culture being the most sensitive commercially available method of diagnosis 1.
- Alternatively, tinidazole 2 grams as a single dose can be used for treatment 1.
- Sexual partners should be treated simultaneously to prevent reinfection, and patients should abstain from sexual activity until both partners complete treatment.
- During pregnancy, metronidazole is still the recommended treatment despite being a category B medication.
Important Considerations
- Untreated infections can increase susceptibility to other STIs including HIV and may lead to complications such as pelvic inflammatory disease in women and prostatitis in men 1.
- Recurrent infections are common and may require extended treatment courses.
- Metronidazole gel is not recommended for use in treating trichomoniasis, as it is considerably less efficacious than oral preparations of metronidazole 1.
From the FDA Drug Label
Symptomatic Trichomoniasis Metronidazole tablets are indicated for the treatment of symptomatic trichomoniasis in females and males when the presence of the trichomonad has been confirmed by appropriate laboratory procedures (wet smears and/or cultures) Tinidazole is indicated for the treatment of trichomoniasis caused by Trichomonas vaginalis. The organism should be identified by appropriate diagnostic procedures.
The diagnosis of Trichomonas vaginalis infection is made by:
- Confirming the presence of the trichomonad by appropriate laboratory procedures, such as:
- Wet smears
- Cultures The treatment for Trichomonas vaginalis infection is:
- Metronidazole tablets for symptomatic trichomoniasis in females and males
- Tinidazole for the treatment of trichomoniasis caused by Trichomonas vaginalis 2 3
From the Research
Diagnosis of Trichomonas vaginalis Infection
- Diagnosis can be confirmed by saline microscopy, OSOM rapid test, or clinical history 4
- Saline microscopy was used to diagnose 45% of cases, OSOM rapid test was used in 40%, and clinical history was used in 15% 4
- APTIMA test was also used to diagnose 23.3% of newly diagnosed cases 4
Treatment of Trichomonas vaginalis Infection
- Metronidazole is a commonly used treatment, with a single 2-g dose being the recommended first-line treatment 5, 6
- Tinidazole is also an effective treatment, with a 2-g single dose being as effective as metronidazole 6
- High-dose regimens of metronidazole or tinidazole may be used for resistant cases, with a cure rate of 90% reported in one study 7
- Multidose metronidazole has been shown to have a lower treatment failure rate compared to single-dose metronidazole, with a pooled risk ratio of 1.87 (95% confidence interval, 1.23-2.82; P < 0.01) 5
- Vaginal paromomycin and desensitization for nitroimidazole allergy are also treatment options for some cases 4
Treatment Failure and Resistance
- Treatment failure can occur due to resistance to metronidazole or tinidazole, with a minimal lethal concentration (MLC) of ≥50 μg/mL for metronidazole and ≥6.3 μg/mL for tinidazole associated with treatment failure 8
- The T. vaginalis susceptibility assay can be used to determine whether treatment failure is due to drug resistance, with an agreement between laboratory result and treatment outcome of 93.7% for metronidazole and 88.9% for tinidazole 8