Metagenomic next-generation sequencing for diagnosis of fatal Balamuthia amoebic encephalitis

Introduction: Balamuthia amoebic encephalitis (BAE), caused by Balamuthia mandrillaris, is a rare and lifethreatening infectious disease with no specific and effective treatments available. The diagnosis of BAE at an early stage is difficult because of the non-specific clinical manifestations and neuroimaging. Case description: A 52 -year -old male patient, who had no previous history of skin lesions, presented to the emergency department with an acute headache, walking difficulties, and disturbance of consciousness. The patient underwent a series of examinations, including regular cerebrospinal fluid (CSF) studies and magnetic resonance imaging, and tuberculous meningoencephalitis was suspected. Despite being treated with anti -TB drugs, no clinical improvement was observed in the patient. Following corticosteroid therapy, the patient developed a rapid deterioration in consciousness with dilated pupils. Metagenomic next -generation sequencing (mNGS) revealed an unexpected central nervous system (CNS) amoebic infection, and the patient died soon after the confirmed diagnosis. Conclusion: This study highlights the application of mNGS for the diagnosis of patients with suspected encephalitis or meningitis, especially those caused by rare opportunistic infections.