New Diagnostic Tests, Treatment Noted for Vaginal Trichomoniasis


SAN FRANCISCO — Trichomoniasis is the cause of about 20% of vaginitis complaints, and there are two new diagnostic tests and one new treatment available for this disorder, Dr. Jeanne Marrazzo said at a conference on contraceptive technology sponsored by Contemporary Forums.

The wet prep remains a valuable diagnostic tool, and metronidazole remains an entirely acceptable treatment, but Dr. Marrazzo, of the University of Washington, Seattle, said that the newer diagnostic techniques are “woefully underused,” and that tinidazole has a number of advantages as a treatment.

Accurate diagnosis is critical because, “Although we think of trich as causing a purulent vaginal discharge, often malodorous, many if not most women with trichomoniasis are asymptomatic,” Dr. Marrazzo said. And a woman may have trichomoniasis even if she hasn't had sex in many months or years. The organism can remain hidden in the subepithelial glands, only to reemerge during a period of antibiotic use or changing hormonal status.

Although Trichomonas can usually be seen in a wet prep, the detection rate increases with practice. It's important to look at the wet prep very quickly; 20% of the organisms disappear within 10 minutes, and they're all gone within a half-hour.

The most common alternative is the BD Affirm VPIII Microbial Identification Test from Becton, Dickinson and Co. Based on nucleic acid hybridization technology, BD Affirm tests for the presence of Trichomonas, Gardnerella, and Candida species. Results take about 45 minutes.

But there are two quicker alternatives. The XenoStrip-Tv T vaginalis test from Xenotope Diagnostics Inc., and the OSOM Trichomonas Rapid Test from Genzyme Corp. both use dipstick technology and return results in about 10 minutes. Compared with wet mounts, these tests have a sensitivity of 67%–83% and a specificity of 98%–100%.

Until recently, metronidazole, either as a single-dose (2 g) or as an oral regimen, was the only treatment for trichomoniasis. Recently, however, single-dose tinidazole (2 g as well) has been added to the treatment guidelines for trichomoniasis, giardiasis, and amoebiasis.

Tinidazole has a better safety and side-effect profile, and women experience much less of the nausea and vomiting commonly seen with metronidazole. The half-life of tinidazole is longer, however, meaning that women must avoid alcohol for 3 days after treatment. Moreover, tinidazole is not safe during pregnancy.

With either metronidazole or tinidazole, systemic treatment is necessary and local treatment is ineffective. Dr. Marrazzo disclosed serving as a consultant or speaker for Ther-Rx Corp., Quindel Corp., Mission Pharmacal Co., Merck & Co., and 3M.

Contemporary Forums and this news organization are wholly owned subsidiaries of Reed Elsevier.

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