Although few patients experienced marked resolution of disseminated cutaneous acanthamebiasis, it appears that the inclusion of 5-flucytosine in the therapeutic regimen was associated with the greatest number of improved cases. In general, a multidrug regimen appears to be more effective than monotherapy. Surgical debridement of affected areas has been beneficial in some cases,13,22 and it should be considered in patients with localized disease, in particular. Topical chlorhexidine has been used adjunctively in some successfully treated cases of cutaneous acanthamebiasis.22,29 In exogenously immunocompromised patients, lowering the dose of the immunosuppressants led to disease-free survival in one patient but had no benefit in 2 other patients,24,27 presumably because of the advanced stage of the disease.
In the present case, our patient's disease initially progressed despite the administration of pentamidine and 5-flucytosine. Stabilization and subsequent resolution of the lesions began after the addition of sulfadiazine and HAART to the therapeutic regimen. In patients with HIV disease and acanthamebiasis, there are no reports demonstrating whether the administration of antiretrovirals can alter the course of the disease. Although sulfonamides have not been used frequently in the treatment of disseminated acanthamebiasis, the utility of sulfonamides in the treatment of Acanthamoeba infection has been shown by Allen and Culbertson,39 who reported that experimental animal infection with Acanthamoeba species can be both prevented and cured with sulfadiazine. Additionally, Cleland et al40 reported improvement in a patient with Acanthamoeba meningoencephalitis who was treated with sulfamethazine, though long-term follow-up was not feasible. Furthermore, Singhal et al35 reported the successful treatment of 2 immunocompetent patients with Acanthamoeba CNS infection using a combination of trimethoprim/ sulfamethoxazole, ketoconazole, and rifampin. These data, combined with the observations of our patient's therapeutic course, suggest that sulfadiazine therapy was important to our patient's clinical improvement and thus should be strongly considered in the treatment of disseminated Acanthamoeba infection. Sulfonamides, however, must be used with caution in patients with HIV/AIDS because of this patient population's high incidence of adverse reactions, especially fever, myalgia, and rash.41
Amebic infections, though rare, have become increasingly recognized in recent years as a result of the emergence of AIDS and the availability of effective immunosuppressive regimens for the prevention of transplant rejection and the treatment of autoimmune diseases. Prompt diagnosis of acanthamebiasis is crucial to a patient's survival because delay in treatment has led to rapid deterioration and death in all reported cases. Although optimal therapy has not been established for this condition, previously reported cases and this case report suggest that efforts to restore the patient's immune system, as well as treatment with a multidrug regimen containing 5-flucytosine and sulfadiazine, may offer the best chance of long-term survival.
Acknowledgment—We would like to thank Cynthia Sears, MD, for her active role in the management of the patient and review of the manuscript.