Emergence of ST11 Klebsiella pneumoniae co-carrying blaKPC-2 and blaIMP-8 on conjugative plasmids.

Klebsiella pneumoniae is a major pathogen with substantial antimicrobial resistance driven by β-lactamase production. The co-existence of carbapenemase genes bla_KPC-2 and bla_IMP-8 in the prevalent K. pneumoniae clone is rare and poses significant clinical challenges in China. In this study, we report the first identification of a clinical ST11 K. pneumoniae strain Kp4874, isolated from a hospitalized patient in China, co-carrying bla_KPC-2 on a ~134 kb IncFII/IncR hybrid plasmid and bla_IMP-8 on a ~75 kb untypable plasmid. Whole-genome sequencing revealed key insertion sequences, including TnAs1 and IS26, facilitating horizontal transfer of these resistance genes. Conjugation experiments confirmed the high transferability of both plasmids, particularly the bla_KPC-2 plasmid. Despite harboring multiple virulence genes, the strain's clinical threat stems primarily from its multidrug-resistant profile. This study highlights the potential for rapid dissemination of such strains in healthcare settings and underscores the critical need for robust surveillance and infection control measures.

Importance: This study is the first to report the co-existence of bla_KPC-2 and bla_IMP-8 in an ST11 Klebsiella pneumoniae strain, underscoring the clinical threat posed by these carbapenemase genes. The identification of bla_KPC-2 on an IncFII/IncR hybrid plasmid, coupled with the successful conjugation of both resistance genes, highlights the significant potential for horizontal gene transfer and multidrug-resistant dissemination. These findings advance our understanding of plasmid-mediated resistance and emphasize the urgent need for enhanced monitoring and infection control strategies to mitigate the spread of such high-risk strains.