Acanthamoeba castellanii encephalitis in a patient with AIDS: a case report and literature review

Amoebic encephalitis is a rare cause of CNS infection for which mortality exceeds 90%. We present the case of a 27-year-old man with AIDS who presented to a hospital in Atlanta (Georgia, USA) with tonic-clonic seizures and headache. His clinical condition deteriorated over several days. Brain biopsy revealed lymphohistiocytic inflammation and necrosis with trophozoites and encysted forms of amoebae. Immunohistochemical and PCR testing confirmed Acanthamoeba castellanii encephalitis, typically described as granulomatous amoebic encephalitis (GAE). No proven therapy for GAE is available, although both surgical and multiagent antimicrobial treatment strategies are often used. Most recently, these include the antileishmanial agent miltefosine. Here we review all cases of GAE due to Acanthamoeba spp in people with HIV/AIDS identified in the literature and reported to the Centers for Disease Control and Prevention. We describe this case as a reminder to the clinician to consider protozoal infections, especially free-living amoeba, in the immunocompromised host with a CNS infection refractory to traditional antimicrobial therapy.