Trichomoniasis

Key Features

• Caused by Trichomonas vaginalis

• Infects 3.7 million people each year in the United States

• Has been associated with adverse pregnancy outcomes

• Urethritis seen in 50% of males who have infection

• Male partners of females with trichomoniasis have a 22% chance of contracting infection

• Urethritis develops in half of males with infection

• Rescreening for T vaginalis at 3 months following initial infection is recommended for women due to the high rate of reinfection

Clinical Findings

• Symptomatic vaginitis with vaginal itching, a green-gray malodorous frothy discharge, and dysuria

• Occasionally postcoital bleeding and dyspareunia may be present

• Vulva may be erythematous

• Cervix may be friable

Diagnosis

• Mixing the discharge with normal saline facilitates detection of the flagellated protozoan on microscopic examination (wet preparation); sensitivity is only 60–70%

• Culture and nucleic acid amplification testing are available when the diagnosis is unclear

• Two FDA-approved, point-of-care antigen-based detection assays for T vaginalis are available

  • However, false-positive results are problematic in populations with low disease prevalence

  • Both antigen assays are performed on vaginal secretions

  • Sensitivity is > 83% and a specificity is > 97%

• Trichomonal urethritis frequently causes a positive urine leukocyte esterase test and white blood cells on urethral smear

Treatment

• Recommended regimens

  • Metronidazole, 2 g orally as a single dose or

  • Tinidazole, 2 g orally as single dose

• Alternative regimen: metronidazole, 500 mg orally twice daily for 7 days