Unraveling the genomic epidemiology and plasmid-mediated carbapenem resistance of Klebsiella pasteurii

This study isolated a <i>Klebsiella pasteurii</i> strain, K1134, from the sputum of an ICU patient, revealing its resistance to the carbapenem antibiotics meropenem and imipenem. Whole-genome sequencing identified a plasmid pK1134-KPC, which carries the carbapenem resistance gene <i>bla</i> _KPC-2. pK1134-KPC, belonging to the IncFII_pCP020359 plasmid group, exhibits a modular structure with <i>bla</i> _KPC-2 embedded in a 32.09 kb accessory region containing multiple accessory genetic elements (AGEs). Comparative genomic analysis of 48 <i>K. pasteurii</i> isolates from 12 countries showed high genetic diversity, with strains clustered into three clades. Notably, <i>K. pasteurii</i> harbors extensive antimicrobial resistance genes across diverse AGEs, classifying it as multidrug-resistant. Twelve <i>bla</i> _KPC-carrying AGEs were identified from the sequences of the isolates, classified into two groups: Tn<i>7551</i> and Tn<i>6296</i>-related elements. The gene clusters for enterotoxins tilimycin and tilivalline, encompassing key regulators and operons, were present in nearly all strains, with incomplete clusters exclusively observed in clade 3 isolates. This study underscores the global dissemination and genetic adaptability of <i>K. pasteurii</i>, highlighting its potential role as a reservoir for resistance genes and emphasizing the need for robust surveillance to mitigate its public health impact.