Persistent and recurrent Trichomonas vaginalis infections: epidemiology, treatment and management considerations

Abstract

Trichomonas vaginalis (TV) is a common sexually transmitted infection that can cause vaginitis, cervicitis and urethritis. Persistent and recurrent TV infections are frequent in women, potentially due to the lack of routine screening recommendations for this pathogen, the chronic nature of some infections, and drug resistance. Metronidazole and tinidazole are two oral drugs that are effective against trichomoniasis. There are few alternative treatment options for persons with a metronidazole allergy or treatment failure. Most TV isolates from women with treatment failures that have been analyzed for susceptibility testing in the United States have exhibited low-level metronidazole resistance, supporting the initial use of tinidazole for patients who fail metronidazole therapy. Several non-nitroimidazole drugs and other agents have demonstrated acceptable in vitro activity or cure rates in case reports for metronidazole-resistant trichomoniasis; however, clinical trials are imperative to evaluate their efficacy as alternative therapeutic regimens for this highly prevalent infection.

Keywords::

• alternative trichomonas therapy
• persistent or recurrent trichomoniasis
• metronidazole resistant T. vaginalis
• Trichomonas vaginalis

Financial & competing interests disclosure

M Hobbs has received research funding from Hologic/Gen-Probe and an honoraria from Becton-Dickinson. The other authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.

No writing assistance was utilized in the production of this manuscript.

Key issues

• Trichomonas vaginalis (TV) is a common sexually transmitted infection that can cause genitourinary infections in both men and women.

• Persistent and recurrent TV infections, which may be due to treatment failures or reinfections, are frequently identified, especially in HIV-infected women.

• Oral, single-dose metronidazole and tinidazole are the only effective recommended treatment regimens for trichomoniasis. However, approximately 5% of TV infections are thought to be associated with metronidazole resistance, and no standard alternative therapies to desensitization exist for women with severe metronidazole allergies.

• Based on in vitro and clinical data, tinidazole is likely to be effective in most women with clinical treatment failures after metronidazole therapy, particularly in those identified with low-level metronidazole resistance (aerobic minimum lethal concentration of 50–100 µg/ml).

• Clinicians treating patients with persistent trichomoniasis who do not respond to longer regimens of metronidazole and/or tinidazole therapy should seek consultation from the US CDC for TV susceptibility testing and potential alternative therapies to the nitroimidazoles.

• Several non-nitroimidazole drugs, plant extracts and other compounds have been identified with good in vitro activity against metronidazole sensitive and resistant TV isolates; however, clinical data on these agents are lacking.

• Case reports have indicated promising cure rates for treatment of metronidazole-resistant TV infections from intravaginal boric acid, furazolidone, paromomycin, oral tinidazole with either amoxicillin, doxycycline, intravaginal tinidazole or clotrimazole.

• Only a few oral and intravaginal non-nitroimidazole treatment regimens have been evaluated in small clinical trials worldwide for treatment of trichomoniasis, including oral Mentha crispa, povidine–iodine intravaginal pessaries and praneem intravaginal tablets.

• Intravaginal metronidazole/miconazole showed some success for treatment of trichomonal infection in a randomized pilot study; however, additional investigations are needed in a Phase III trial and its applicability for patients with metronidazole-resistant TV or metronidazole allergy is unclear.

• The next 5 years should focus on identifying new drug therapies for trichomoniasis, considering its public health impact and the growing concern about the management of drug-resistant sexually transmitted infections.

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