Utility of Metagenomic Next-Generation Sequencing for Diagnosis of Infectious Diseases in Critically Ill Immunocompromised Pediatric Patients.

Purpose: Infections cause high rates of illness and death in children worldwide. However, studies on the clinical value of metagenomic next-generation sequencing (mNGS) for immunocompromised children are still limited.

Patients and methods: From June 2021 to December 2023, 119 samples were collected at Pediatric Intensive Care Unit (PICU) of a single-center pediatric hospital and classified into two groups based on their immune states. We compared the diagnostic performance of mNGS and conventional microbiological test (CMT) for pathogen identification, and assessed the clinical impacts of mNGS.

Results: Among the 119 samples, 48 (40.34%) belonged to the immunocompromised children. mNGS had a higher positivity rate than CMT (76.47% vs 55.46%, P = 0.0006). The positive percent agreement (PPA) of mNGS for immunocompromised children was higher compared to immunocompetent children (95.24% vs 77.78%). The most common pathogens for immunocompromised patients were gram-negative bacteria and herpesvirus. However, immunocompetent children showed a higher detection rate for gram-positive bacteria and respiratory viruses. Furthermore, the proportions of the positive impact of mNGS results were significantly higher in immunocompromised patients compared to immunocompetent patients for both diagnosis (91.67% vs 57.75%) and treatment (95.83% vs 64.79%) (P < 0.0001). Immunocompromised state, length of hospital stays, times stay in ICU, Pediatric Risk of Mortality (PRISM) score, neutrophil percentage (NEUT%) and the ratio of arterial oxygen partial pressure to fractional inspired oxygen (PaO2/FiO2) were considered independent factors for poor prognosis in critically ill pediatric patients.

Conclusion: In patients from PICU, mNGS had a greater clinical significance in immunocompromised children compared to immunocompetent children. mNGS technology is an important auxiliary method for achieving accurate diagnosis and treatment of critically ill pediatric patients.