Acanthamoeba meningoencephalitis after bone marrow transplantation

Two patients presented with fever and nodular pulmonary infiltrates 9 and 6 months after marrow transplantation for leukemia. The second patient also had painful subcutaneous nodules that subsequently ulcerated. Both had a history of sinusitis and both had recently been treated with corticosteroids. During treatment with antibacterial and antifungal antibiotics, they developed rapid mental deterioration, coma and/or seizures. CT findings included hydrocephalus with extensive cortical and periventricular hypodensities in the first patient, and hydrocephalus with a cerebellar hemorrhage and edema in the second patient. Cerebrospinal fluid had a low glucose and elevated protein levels with few erythrocytes and little or no pleocytosis. Despite therapy with broad-spectrum antibiotics, including coverage for opportunistic infections, both patients died. Autopsy revealed Acanthamoeba species causing necrotizing meningoencephalitis, pneumonitis and adrenalitis in the first patient and causing necrotizing meningoencephalitis and dermatitis in the second patient. While these are the only reported cases of disseminated Acanthamoeba infection in marrow transplant recipients, a review of the literature suggests that this organism may be a new cause of opportunistic infections.