The application of shotgun metagenomics to the diagnosis of granulomatous amoebic encephalitis due to Balamuthia mandrillaris: a case report

• DOI: 10.1186/s12883-021-02418-y
• Publication Date: 2021-10-10T19:18:54Z
• Authors: Shota Hirakata; Yusuke Sakiyama; Akiko Yoshimura; Mei Ikeda; Katsunori Takahata; Yuichi Tashiro; Michiyoshi Yoshimura; Hitoshi Arata; Hajime Yonezawa; Mari Kirishima; Michiyo Higashi; Miho Hatanaka; Takuro Kanekura; Kenji Yagita; Eiji Matsuura; Hiroshi Takashima
• Keywords: 0303 health sciences; Shotgun metagenomics; Granuloma; Granulomatous amoebic encephalitis; Case Report; Amebiasis; Balamuthia mandrillaris infection; Middle Aged; Balamuthia mandrillaris; 3. Good health; 03 medical and health sciences; Next-generation sequencer; Encephalitis; Humans; Female; Necrotizing encephalitis; Neurology. Diseases of the nervous system; Metagenomics; RC346-429

Abstract Background Granulomatous amoebic encephalitis (GAE) is an infrequent and fatal infectious disease worldwide. Antemortem diagnosis in this condition is very difficult because clinical manifestations and neuroimaging are nonspecific.

Case presentation A 60-year-old Japanese woman was admitted with a chief complaint of left homonymous hemianopsia. Brain-MRI showed extensive necrotizing lesions enhanced by gadolinium, in the right frontal lobe, right occipital lobe, and left parietal lobe. Epithelioid granulomas of unknown etiology were found in the biopsied brain specimens. Shotgun metagenomic sequencing using a next-generation sequencer detected DNA fragments of Balamuthia mandrillaris in the tissue specimens. The diagnosis of granulomatous amoebic encephalitis was confirmed using an amoeba-specific polymerase chain reaction and immunostaining on the biopsied tissues.

Conclusions Shotgun metagenomics is useful for the diagnosis of central nervous system infections such as GAE wherein the pathogens are difficult to identify.