Case report: A toxoplasmic encephalitis in an immunocompromised child detected through metagenomic next-generation sequencing.

There exist numerous pathogens that are capable of causing infections within the central nervous system (CNS); however, conventional detection and analysis methods prove to be challenging. Clinical diagnosis of CNS infections often depends on clinical characteristics, cerebrospinal fluid (CSF) analysis, imaging, and molecular detection assays. Unfortunately, these methods can be both insensitive and time consuming, which can lead to missed diagnoses and catastrophic outcomes, especially in the case of infrequent diseases. Despite the application of appropriate prophylactic regimens and evidence-based antimicrobial agents, CNS infections continue to result in significant morbidity and mortality in hospital settings. Metagenomic next-generation sequencing (mNGS) is a novel tool that enables the identification of thousands of pathogens in a target-independent manner in a single run. The role of this innovative detection method in clinical pathogen diagnostics has matured over time. In this particular research, clinicians employed mNGS to investigate a suspected CNS infection in a child with leukemia, and unexpectedly detected Toxoplasma gondii. Case: A 3-year-old child diagnosed with T-cell lymphoblastic lymphoma was admitted to our hospital due to a 2-day history of fever and headache, along with 1 day of altered consciousness. Upon admission, the patient's Glasgow Coma Scale score was 14. Brain magnetic resonance imaging revealed multiple abnormal signals. Due to the patient's atypical clinical symptoms and laboratory test results, determining the etiology and treatment plan was difficulty.Subsequently, the patient underwent next-generation sequencing examination of cerebrospinal fluid. The following day, the results indicated the presence of Toxoplasma gondii. The patient received treatment with a combination of sulfamethoxazole (SMZ) and azithromycin. After approximately 7 days, the patient's symptoms significantly improved, and they were discharged from the hospital with oral medication to continue at home. A follow-up polymerase chain reaction (PCR) testing after about 6 weeks revealed the absence of Toxoplasma. Conclusion: This case highlights the potential of mNGS as an effective method for detecting toxoplasmic encephalitis (TE). Since mNGS can identify thousands of pathogens in a single run, it may be a promising detection method for investigating the causative pathogens of central nervous system infections with atypical features.

Case Report: A Candida Meningitis in an Immunocompetent Patient Detected Through the Next-Generation Sequencing.

Background: Fungal infections of the central nervous system (CNS) are not commonly seen clinically. Clinical diagnosis of fungal infections often depend on the pathogen culture and the clinical features. This method is time-consuming and insensitive, which can lead to misdiagnosis. The authors introduce an adult patient with fungal infections diagnosed by next-generation sequencing (NGS). Case: The patient was a 60-year-old male Chinese who had both hypermyotonia of the lower extremities and fever. The auxiliary examinations such as MRI, CT, and cerebrospinal fluid (CSF) analysis showed obvious abnormalities. Because of the difficulties in diagnosis, it was hard to determine the treatment plan. The NGS detected specific sequences of Candida albicans in 3 days. The patient was then treated with liposomal amphotericin B and fluconazole. About 3 weeks later, the symptoms of the patient improved significantly and he was discharged from the hospital. Conclusion: Compared with the routine cultural method, NGS has made a huge advancement in infection diagnosis and targeting antimicrobial therapy for CNS infection.