T. vaginalis, a parasitic protozoon, causes trichomoniasis. The infection is spread through sexual contact and causes vaginitis in women and, in some cases, urethritis in men. The majority of men are asymptomatic carriers. The infection is classified as a STI, occurs frequently with gonorrhea and Chlamydia infections, and has been linked to increased HIV transmission rates.
T. vaginalis infection has been linked to low birth weight, premature rupture of membranes, and preterm delivery in pregnant women.
Symptoms of trichomoniasis
Although some patients are asymptomatic, trichomoniasis is distinguished by a green-to-yellow frothy vaginal discharge, malodor, pruritus, irritation, dysuria, dyspareunia, and vaginal mucosa erythema. Because of punctuate hemorrhages, patients may present with a “strawberry cervix.” Males are usually asymptomatic, but they can develop urethritis.
Diagnosis of trichomoniasis
Trichomoniasis is typically diagnosed using a wet mount examination and microscopical visualization of motile trichomonads in a fresh specimen; however, this method has a sensitivity of only 60% to 70%. 5 To preserve the organism’s viability, the test must be performed within 2 hours of specimen collection. T. vaginalis infections also include WBCs and lactobacilli bacteria. The amine test from the KOH preparation will be positive if the vaginal pH is greater than 4.5.
If the wet mount tests negative for motile trichomonads, a culture in Diamond’s medium or a commercially available pouch system (InPouch TV, Biomed Diagnostics, White City, OR) is recommended for T. vaginalis detection. The Affirm VPIII DNA probe test system (Becton, Dickinson, Franklin Lakes, NJ) and the OSOM Trichomonas Rapid Test (Genzyme Diagnostics, Cambridge, MA) point-of-care antigen detection tests have increased sensitivity and specificity for T. vaginalis.
How to treat trichomoniasis
Metronidazole is the recommended treatment for trichomoniasis. Tinidazole, a newer drug, is available for patients who develop an allergy to metronidazole or for whom treatment is ineffective. To avoid reinfection, all patients’ sexual partners, even if asymptomatic, should be treated.
The Food and Drug Administration has expanded the approval of Solosec® (secnidazole) to include treatment of trichomoniasis caused by Trichomonas vaginalis in adults. A single oral dose of secnidazole increased microbiological cure rates among women with trichomoniasis who were enrolled in a randomized controlled trial in the United States, including women with HIV or bacterial vaginosis.
- Centers for Disease Control and Prevention: Diseases characterized by vaginal discharge. Sexually Transmitted Diseases Treatment Guidelines, 2010. http://www.cdc.gov/std/ treatment/2010/vaginal-discharge.htm
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- Patil, MJ, Magamoti, JM, and Metgud, SC: Diagnosis of Trichomonas vaginalis from vaginal specimens by wet mount microscopy, in pouch TV culture system, and PCR. J. Global Infect Dis [serial online] [cited 2012 Jul 6] 4:22–25, 2012. Web site: http://www.jgid.org/text.asp?2012/4/1/22/ 93756 10. Keen, EF, and Aldous, WK: Genial infections and sexually transmitted diseases. In Mahon, CR, Lehman, DC, Maneselis, G: Textbook of Diagnostic Microbiology, ed 4, Saunders Elsevier, Maryland Heights, MO, 2011.