New treatment option for trichomoniasis?
The next patient in your exam room is a young woman who has a frothy, yellow-green vaginal discharge with a strong odor. She reports discomfort during intercourse and urination. What’s your initial diagnosis and plan of treatment?
If trichomoniasis is your call following a vaginal culture or wet mount, you have just diagnosed another case of the most common curable sexually transmitted disease (STD) in young, sexually active women. An estimated 5 million new cases occur each year in women and men, according to the Centers for Disease Control and Prevention (CDC).
Oral therapeutic options are limited to one drug: metronidazole (Flagyl, G.D. Searle & Co., Chicago), a first-generation 5-nitroimidazole. The CDC recommends 2 g orally in a single dose; an alternative regimen is 500 mg twice a day for seven days.1
Metronidazole has proved to be an effective drug for most cases of trichomoniasis. In randomized clinical trials, the recommended metronidazole regimens have resulted in cure rates of approximately 90%-95%.1
Resistance is a problem
But what are your options when you encounter a patient with recalcitrant trichomoniasis? Clinical treatment failures and in-vitro resistance to metronidazole have been reported.2 Since trichomoniasis is not a reportable disease and culture specimens routinely are not obtained for diagnosis, the prevalence of metronidazole-resistant strains is not known.2
Treatment of patients with metronidazole-refractory vaginal trichomoniasis constitutes a major therapeutic challenge, and treatment options are extremely limited, says Jack Sobel, MD, professor of medicine and chief of the division of infectious diseases at Wayne State University in Detroit.
Sobel has published initial research of tinidazole, a second-generation 5-nitroimidazole, for treatment of metronidazole-resistant vaginal trichomoniasis.3 His research reports a cure rate of 22 (92%) of 24 patients with refractory trichomoniasis who were treated with high doses of oral and vaginal tinidazole.
While tinidazole has been available in Europe for a number of years, it has not been marketed in the U.S. However, the drug now is under development by an Arlington Heights, IL, company, Presutti Laboratories, for introduction in the United States.
"As no other alternative therapy to metronidazole for trichomoniasis exists in the U.S., we feel that there is a medical need that tinidazole can fill," says Dawn Flynn, company vice president. "We plan to seek [Food and Drug Administration] approval for tinidazole."
Understand the STD
Trichomoniasis is caused by the single-celled protozoan parasite Trichomonas vaginalis. According to the CDC, the vagina is the most common site of infection in women, while the urethra is the most common site of infection in men. Women may have a frothy, yellow-green vaginal discharge with a strong odor, irritation, and itching in the genital area, and discomfort during intercourse and urination. Most men with trichomoniasis do not have signs or symptoms; those who do may have an irritation inside the penis, mild discharge, or slight burning after urination or ejaculation. Symptoms usually appear within five to 28 days of exposure in women.
Trichomoniasis is a concern in pregnant women since it may cause premature rupture of the membranes and preterm delivery. The genital inflammation caused by the STD also might increase a woman’s risk of acquiring HIV infection if she is exposed to the virus.
Treat the infection
When discussing treatment with your female patients, explain the importance of treating their male partners as well. Tell them that a man, who may never have symptoms or whose symptoms have stopped, can continue to infect a female partner until he has been treated. Therefore, plan to treat both partners at the same time to eliminate the parasite. The CDC recommends that persons being treated for trichomoniasis should avoid sex until treatment is completed and they have no symptoms. Patients should be instructed not to consume alcoholic beverages during metronidazole treatment and for at least three days afterward because abdominal cramps, nausea, headaches, and flushing may occur.
Trichomoniasis usually can be cured with the regimens recommended by the CDC. If treatment failure repeatedly occurs, the CDC advises treatment with a single 2-g dose of metronidazole once a day for three to five days. Patients with culture-documented infection who do not respond to such therapy should be managed in consultation with an expert; such consultation is available from the CDC.
References
1. Centers for Disease Control and Prevention. 1998 guidelines for treatment of sexually transmitted diseases. MMWR 1998; 47:74.
2. Workowski KA. Resistant sexually transmitted diseases. Presented at the 2001 Annual Session of the American College of Physicians-American Society of Internal Medicine. Atlanta; March 2001.
3. Sobel JD, Nyirjesy P, Brown W. Tinidazole therapy for metronidazole-resistant vaginal trichomoniasis. Clin Infect Dis 2001; 33:1,341-1,346.
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