First Identification of blaNDM-16b-Harboring IncX3 Plasmid in Pediatric Klebsiella pneumoniae Reveals Cross-Species Dissemination and Clinical Risk Patterns

<title>Abstract</title> <p> Multidrug-resistant <italic>Klebsiella pneumoniae</italic> (MDR-KP) is a growing public health threat to children worldwide, but its genetic traits and clinical risk factors in pediatric patients are not well understood. To address this, we collected 39 MDR-KP isolates from 37 pediatric patients. We used whole-genome sequencing (WGS) to analyze their genomic features and examined statistical links between antimicrobial resistance (AMR) profiles and clinical data. Our results show that AMR patterns were significantly associated with bacterial genomic features (such as sequence type, number of resistance genes, and virulence gene count), patient factors (mode of delivery, gravidity, parity, age and admission weight), and clinical details (specimen type, admitting department and affected organ system). Specifically, ST11-type <italic>K. pneumoniae</italic> showed much higher resistance to sulfonamides (OR = 24.135, 95% CI: 1.656 <bold>–</bold> 351.801, <italic>P</italic>  = 0.020). Notably, we detected the <italic>bla</italic> _NDM−16b for the first time in a pediatric case, carried by a highly resistant strain (ETFK5283) on an IncX3 plasmid. Genetic analysis indicated this plasmid is closely related to one (pTMTA85711, AP024206) previously found in an <italic>Escherichia coli</italic> isolate from Tokyo, Japan. These findings highlight the urgent need for pediatric-focused genomic surveillance, tailored antibiotic use, and stronger infection control measures to manage high-risk MDR-KP in children. </p>