Background Rescreening women for Trichomonas vaginalis (TV) post treatment is important as repeat infections are common, ranging from 5%–31%. Nucleic acid amplification testing (NAAT) too soon after treatment may result in false positive results due to detection of remnant TV nucleic acids. The goal of this study was to determine the rate of false positive NAAT results at weeks 1–4 post treatment completion using culture as the gold standard.
Methods Women attending an STI clinic in New Orleans who were InPouch culture positive and treated with metronidazole (MTZ) were included. Participants were scheduled for 4 weekly follow up visits beginning one week post-treatment completion. They provided self-obtained vaginal swabs (SOVS) and information regarding sexual exposure at each visit. SOVS were tested using InPouch culture and the Gen-Probe AptimaTV (GPATV) assay which targets ribosomal RNA. Women who were culture positive at follow-up were considered re-infected/treatment failure and were not followed further.
Results 39 women were InPouch+ at baseline and were followed. Of these, 3 (7.7%) were InPouch TV+ at follow-up (1 at 1 week and 2 at 2 weeks) and reported no sexual exposure. Thus, these women were considered to be treatment failures and were no longer followed. Of the remaining cases, 5/29 (17.2%) were GPATV+ at the 1 week follow up visit, and 1/34 (2.9%) was GPATV+ at 2 weeks. The six positive women denied vaginal sexual re-exposure. None of the women were InPouch TV culture positive at any of the follow up visits and no woman was GPATV+ at 3 and 4 weeks post treatment.
Conclusions These data demonstrate that TV ribosomal RNA is cleared from the vagina by 3 weeks post completion of successful MTZ treatment and that the GPATV assay can be relied on as a test-of-cure at this point and beyond.
Disclosure Drs Martin and Taylor have served as consultants for Hologic Inc.