Trichomoniasis | Questions & Answers | 2015 STD Treatment Guidelines

Question: Are there any recommendations for the treatment of trichomonas in a person with a metronidazole allergy?

T. vaginalis treatment options are limited in patients with IgE mediated-type allergy to nitroimidazoles (metronidazole and tinidazole).  Referral to a specialist for desensitization according to a published regimen is recommended (Helms et al. J OB/GYN 2008;198:e371–7). There have been a few case reports of success with use of vaginal paromomycin to treat trichomonas in women with metronidazole allergy. (Nyirgesy et al. CID 1998;26:986–8. Keating et al. STD 2015;42:482–5). Paromomycin needs to be compounded by a pharmacist and should be administered with precautions of possible local adverse events (application of vaseline to the vulva to prevent ulcers was successful in a recent review of vaginitis patients who received paromomycin {Keating et al. STD 2015;42:482-5}).

Question: When is it recommended to test males for trichomonas, and should we test or treat male partners of women who have trichomoniasis?

There are no current recommendations to test asymptomatic males for trichomonas. However, male partners of women treated for trichomoniasis should receive presumptive treatment for trichomoniasis. If testing is available, then these male partners could be offered testing as well, however, understanding the limitations of diagnostics is important in interpreting test results.  Testing should not delay or alter recommended presumptive treatment of these male partners..

Testing for trichomonas with NAATs (nucleic acid amplification tests) can be used in men (urine or urethral swabs) if laboratory has validated per CLIA regulations. Several large reference laboratories have performed the necessary CLIA validation. NAAT testing has much higher sensitivity than wet mount microscopy. Wet mount microscopy can be used for detection from male specimens (e.g. urethral, urine sediment, and semen) but has very low sensitivity (<51%). Culture has higher sensitivity than wet mount and was considered the gold standard prior to development of NAATs. Culture has highest specificity (up to 100%), but is less sensitive than NAAT.  Culture testing from men requires a urethral swab, urine sediment, and/or semen, and multiple specimens can be used to inoculate a single culture as a way to enhance yield.

T.vaginalis can cause urethritis in men who have sex with women (MSW) and is an important etiology to consider in men with persistent or recurrent urethritis.  NAAT testing for T. vaginalis can be obtained in these men (if available).  In areas where T. vaginalis is prevalent, men who have sex with women with persistent or recurrent urethritis should be presumptively treated with metronidazole 2 g orally in a single dose, or tinidazole 2 g orally in a single dose, to cover T.vaginalis.