Long-term management of refractory vaginal trichomoniasis following initial metronidazole treatment failure: A case series

Guidelines for sexually transmitted infections recommend oral metronidazole (MNZ) as the first-line treatment option for vaginal trichomoniasis; however, there have been cases of prolonged symptoms or recurrence after treatment. To consider appropriate treatment strategies for refractory vaginal trichomoniasis, we conducted a retrospective cohort study. We reviewed the medical records of patients who tested positive for Trichomonas vaginalis (T. vaginalis) at the National Center for Global Health and Medicine between August 2011 and May 2023. Refractory vaginal trichomoniasis was defined as the failure after the initial MNZ treatment. During the study period, nine cases of vaginal trichomoniasis were identified, six of which were refractory to treatment for T. vaginalis. Four patients were cured with a combination of oral and vaginal tinidazole (TNZ) therapy, one with oral TNZ and one with two doses of MNZ. Possible causes of treatment failure include MNZ-resistant T. vaginalis, reinfection between partners, and infections of other sexual transmitted diseases. However, the fact that TNZ was effective suggests that MNZ-resistant T. vaginalis may have been the cause. Although MNZ resistance testing was not performed in this study, treatment with TNZ should be considered in cases of refractory vaginal trichomoniasis, possibly caused by MNZ-resistant T. vaginalis.