Clinical Pathology: Microbiology

802) A 23-year-old woman presented to her doctor with a vaginal discharge that was frothy and malodorous (i.e., “fishy odor”). Which one of the following parasites is the most likely cause of her infection?

Trichomonas vaginalis is a protozoan parasite with only a trophozoite stage. It is characterized by four to five flagella and an undulating membrane, which are responsible for its motility. It is transmitted sexually, and its presence in children is highly suggestive of sexual abuse.

• Trichomoniasis presents with an elevated vaginal pH, an amine odor, and frothy or milky discharge. In men, T. vaginalis is detected most commonly from urine and urethral specimens.

• Culture is the gold standard for diagnosis of trichomoniasis. Pouches with specific growth media are inoculated, incubated for 2 to 5 days, and flagellated. T. vaginalis are viewed microscopically. Wet mount preparations of vaginal discharge for observing the motile parasite are highly insensitive. Nucleic acid amplification tests are commercially available, have high sensitivity, and have a rapid turn-around time to results.

• Only about 5% of women with trichomoniasis present with “strawberry cervix” (i.e., colpitis macularis), but when seen, it is highly specific for this infection. This presentation results from microscopic, punctuate petechiae on the cervix.

• Metronidazole or tinidazole are the treatments of choice for trichomoniasis.

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