A 41-year-old Mexican male presented with a 5-month history of simple partial seizures that were initially treated with valproic acid. Upon admission to a hospital in Monterrey, Mexico, he experienced progressive deterioration in consciousness, intense headache, vomiting, and recurrent seizure episodes. His past medical history was unremarkable. A magnetic resonance imaging scan revealed a frontoparietal tumor in the right cerebral hemisphere with a midline shift, which was suspected to be a primary cerebral glioma. The patient underwent a surgical excision of the brain lesion. The postoperative histological diagnosis was granulomatous amebic encephalitis. Biopsy examination using the Gömöri trichrome stain demonstrated the presence of numerous Acanthamoeba cysts and trophozoites (Figure A, 200X). The patient was treated with a combination of rifampin, trimethoprim/sulfamethoxazole, fluconazole, and metronidazole; amphotericin B was eventually added to the regimen. The patient died 3 months after the initial diagnosis of granulomatous amebic encephalitis. Acanthamoeba sp. infection was confirmed postmortem through immunohistochemical staining.
Granulomatous amebic encephalitis is a serious infection of the brain and spinal cord caused by the free-living ameba Acanthamoeba spp. or Balamuthia spp., when contaminated water enters the nose of a human host. Acanthamoeba is a eukaryotic genus of microorganisms that cause rare but severe infections of the eye, central nervous system, and skin. As free-living protozoans, Acanthamoeba species are found in environmental sources such as water and soil1–3. A retrospective review of the case revealed a history of exposure to water from a tank connected to a waterwheel, offering a likely explanation for infection acquisition.
