Subacute Balamuthia mandrillaris encephalitis in an immunocompetent patient diagnosed by next-generation sequencing

Balamuthia mandrillaris is a free-living heterotrophic amoeba found in soil that causes a rare and usually fatal granulomatous amebic encephalitis. We report an immunocompetent patient infected with B. mandrillaris encephalitis diagnosed by next-generation sequencing (NGS). Clinical manifestations included sudden headache and epilepsy with disturbance of consciousness. The opening pressure of cerebrospinal fluid (CSF) was 220 mmH₂O, with mildly elevated white blood cell numbers and elevated protein levels. Cranial magnetic resonance imaging revealed abnormal signals in the right frontal lobe, left parietal lobe, and left occipital lobe. CSF NGS detected B. mandrillaris. Albendazole and metronidazole combined with fluconazole were administered to the patient immediately, but his condition deteriorated and he eventually died. Encephalitis caused by B. mandrillaris is rare and has a high mortality rate. Clinical manifestations are complex and diverse, but early diagnosis is very important for successful treatment. This can be aided by the metagenomic NGS of CSF.