Metagenomic analysis using next-generation sequencing of pathogens in bronchoalveolar lavage fluid from pediatric patients with respiratory failure

Next-generation sequencing (NGS) has been applied in the field of infectious diseases. Bronchoalveolar lavage fluid (BALF) is considered a sterile type of specimen that is suitable for detecting pathogens of respiratory infections. The aim of this study was to comprehensively identify causative pathogens using NGS in BALF samples from immunocompetent pediatric patients with respiratory failure. Ten patients hospitalized with respiratory failure were included. BALF samples obtained in the acute phase were used to prepare DNA- and RNA-sequencing libraries. The libraries were sequenced on MiSeq, and the sequence data were analyzed using metagenome analysis tools. A mean of 2,041,216 total reads were sequenced for each library. Significant bacterial or viral sequencing reads were detected in eight of the 10 patients. Furthermore, candidate pathogens were detected in three patients in whom etiologic agents were not identified by conventional methods. The complete genome of enterovirus D68 was identified in two patients, and phylogenetic analysis suggested that both strains belong to subclade B3, which is an epidemic strain that has spread worldwide in recent years. Our results suggest that NGS can be applied for comprehensive molecular diagnostics as well as surveillance of pathogens in BALF from patients with respiratory infection.