Central nervous system nocardiosis diagnosed by metagenomic next-generation sequencing: A case series and literature review

Background. Central nervous system (CNS) nocardiosis is a rare suppurative disease caused by the genus Nocardia. It is found most frequently in immunocompromised individuals. Objectives. In this study, we retrospectively reviewed the clinical presentations, laboratory examination, therapy and outcomes of 9 patients with CNS nocardiosis diagnosed using metagenomic next-generation sequencing (mNGS) in our hospital. Materials and methods. We reviewed 9 patients with confirmed diagnosis of CNS Nocardia infection from January 2017 to December 2021 in the Department of Neurology at The Third Affiliated Hospital, Sun Yat-sen University (Guangzhou, China). In addition, we searched literature related to CNS Nocardia infection on PubMed and included all case reports with proven CNS nocardiosis since 2016. Results. The metagenomic next-generation sequencing (mNGS) of CSF can be used for the rapid diagnosis of nocardiosis in CNS and N. farcinica are the most commonly isolated species. Underlying autoimmune diseases, immunosuppressive agents including corticosteroids and organ transplantation are predisposing factors of developing CNS nocardiosis. Single or multiple hyper-enhanced ring lesions indicative of cerebral abscesses are commonly presented in brain imaging. Trimethoprim-sulfamethoxazole (TMP-SMX) is used as the primary agent for the antibacterial therapy and in combination with other antibacterial agents. Conclusions. Our study demonstrated that mNGS of CSF can be conducted for definitive and rapid diagnosis for CNS nocardiosis.