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May 2001
Diagnosis: Acanthamoeba infection
The organism was identified morphologically and by monoclonal antibody staining at the Centers for Disease Control and Prevention in Atlanta as belonging to the genus Acanthamoeba. A subsequent lung biopsy revealed the same organism.
Ancanthamoeba is found in soil, fresh water, dust, and sewage worldwide. It can cause keratitis in immunocompetent hosts with a history of fresh water swimming or use of corrective contact lenses. The amoeba is most likely acquired by inhalation or direct contact with contaminated soil and spreads hematogenously. Acanthamoeba can be difficult to distinguish histologically, often being mistaken for inflammatory debris or histiocytes.
Most HIV-infected adults with Ancanthamoeba have had isolated cutaneous involvement. Disseminated infection, as in this patient, occurs less frequently. Few cases of disseminated infection have been treated successfully. This patient was treated with a combination of intravenous fluconazole, oral flucystosine, and oral sulfadiazine. Although his condition improved, the infection was never completely eradicated.
Other treatment regimens that have been utilized include intravenous pentamidine and oral itraconazole, with or without oral flucytosine. Topical treatment with antifungal agents also has been utilized as an adjunct. Most successfully treated cases have been diagnosed before central nervous system involvement was noted. Continued study of the best multi-drug regime for treatment is necessary.
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