Emergence of Pediatric Sepsis Caused by a <i>Klebsiella pneumoniae</i> Strain Coharboring <i>bla</i> _NDM-1 , <i>bla</i> _OXA-1 , and <i>Mcr-9</i> in China

This study reports the discovery of a <i>Klebsiella pneumoniae</i> (KPN) strain carrying the <i>bla</i>_NDM-1, <i>bla</i>_OXA-1, and <i>mcr-9</i> genes in China for the first time. This strain was isolated from the blood of a 2-year-old pediatric patient with acute lymphoblastic leukemia and sepsis. The strain exhibited high resistance to various antibiotics, including β-lactams, carbapenems, and ceftazidime-avibactam. Through whole-genome sequencing and comparative genomic analysis, we found that these resistance genes coexisted on the transferable IncHI2/IncHI2A-type plasmid pK708696_1, which showed high similarity to plasmid pK710429_2 from strain KPN710429 previously identified in our hospital, indicating their potential for rapid spread through horizontal gene transfer. We also performed conjugation experiments to verify the transferability of the plasmid. The results show that the resistance of this strain to traditional antibiotics significantly limited clinical treatment options, thereby posing a serious threat, especially for pediatric leukemia patients with compromised immune systems. This study provides important scientific evidence and new therapeutic approaches for combating carbapenem-resistant <i>Klebsiella pneumoniae</i> infections and highlights the urgency of developing new antibiotics and alternative therapies.