Resolution of resistant vaginal trichomoniasis associated with the use of intravaginal nonoxynol-9

An otherwise healthy, sexually inactive woman was determined by in vitro susceptibility testing to have vaginal infection by a strain of Trichomonas vaginalis with high-grade metronidazole resistance. Prolonged high-dose oral and intravaginal metronidazole therapy did not resolve the infection, but caused temporary peripheral neuropathy. Tinidazole was ineffective as well. Serendipitous use of topical intravaginal nonoxynol-9 for contraception appeared to resolve the infection. We reviewed reinfection, noncompliance with therapy, and concomitant use of other drugs that degrade the efficacy of metronidazole as possible causes of falsely "resistant" trichomoniasis. The literature suggests that mebendazole, furazolidone, and anisomycin may be effective for treatment of metronidazole-resistant trichomoniasis. This case and previously published laboratory data suggest that intravaginal nonoxynol-9 deserves further study as a treatment for resistant trichomoniasis, though trichomonal coinfection of the patient's urethra, Skene glands, and sexual partner would not likely be resolved by such therapy.