Genomic dissection of the clonal background and global dissemination of hypervirulent Klebsiella pneumoniae CG23-KL57 lineage

The emergence of multidrug-resistant and hypervirulent Klebsiella pneumoniae represents a growing threat to global public health. Here we investigate the genomic epidemiology and evolutionary dynamics of emerging K. pneumoniae clonal group 23 (CG23) lineages, with a particular focus on ST218-KL57 (predominantly found in Asia) and ST23-KL57 (circulating in Europe) to understand how genomic recombination and adaptive evolution drive the convergence of hypervirulence and multidrug resistance in CG23. We analyzed 3,118 clinical isolates from China together with 75,954 publicly available genomes, encompassing 122 ST218-KL57 and 45 ST23-KL57 isolates; 13 ST218-KL57 isolates were newly sequenced. Phylogenetic analyses revealed that ST23-KL57 forms a distinct subclade within CG23, more closely related to ST218-KL57 than to the classical ST23-KL1 linage. Neither ST218-KL57 nor ST23-KL57 harbors the chromosomal virulence loci (GIE492 and all island), which are characteristic of hypervirulent ST23-KL1. ST23-KL57 simultaneously harbors dual carbapenemases and key virulence genes (peg-344, iucA, rmpADC, and rmpA2), reflecting its hybrid origin of approximately 80% Asian hypervirulent ST218-KL57 and 20% European multidrug-resistant ST395 linage. The genomic decay of the iroBCDN operon in ST23-KL57 suggests an adaptive trade-off between antimicrobial resistance and virulence. These findings underscore the importance of enhanced genomic surveillance and refined risk assessment for the evolving CG23-KL57 lineage.