Purpose: Klebsiella oxytoca  is an opportunistic pathogen causing nosocomial infections. This study was designed to characterize the genomic features of a carbapenem-resistant K. oxytoca  strain and analyze its molecular characteristics.
Materials and Methods: The strain wzx-IMP was isolated from the blood of a 2-year-old girl diagnosed with acute myeloid leukemia-M7. Species identification was performed, and the minimal inhibitory concentration of the strain was measured. Multilocus sequence typing was performed to identify the subtypes of K. oxytoca . The transfer capacity of the blaIMP-4-harboring plasmid was investigated by conjugation experiments, and the genome characteristics of the strain were examined using whole-genome sequencing.
Results: wzx-IMP belongs to the ST85 type and is resistant to imipenem and meropenem, which harbored the blaIMP-4 gene. The blaIMP-4 gene was located in an IS26-associated class 1 integron of pwzx_IMP, which contains conserved IncN1-type backbone regions with a replication gene and its accessory structure for plasmid replication. The blaIMP-4-carrying plasmid in wzx-IMP was successfully transferred to Escherichia coli  EC600 by conjugation. Whole-genome sequencing showed that the wzx-IMP isolate included the blaOXY-1-1 gene, accompanied by OmpK36 absence.
Conclusion: We report an ST85-type carbapenem-resistant K. oxytoca  strain, which produces blaIMP-4 located in an IncN1-type plasmid and accompanied by OmpK36 porin deficiency.
Keywords: Klebsiella oxytoca , blaIMP-4, ST85, IncN1, OmpK36