Genomic evidence for putative insertion sequence-associated chromosomal integration of aerobactin virulence loci in ST11 carbapenem-resistant

Background: The global rise in hypervirulent carbapenem-resistant Methods: Whole-genome sequencing and comparative genomic analyses were performed on 112 locally collected carbapenem-resistant Results: Among 66 hv-CRKP identified locally, the ST11-KL64 lineage was dominant, accounting for 87.9%. As against the classical fusion-plasmid model, these isolates harbored candidate chromosomal virulence-locus configurations, supported by convergent short-read sequencing evidence, with insertion sequences identified at or near the inferred breakpoint regions. IS-positive hv-CRKP isolates included in the phenotypic comparison showed significantly greater virulence in Conclusion: This study identified recurrent candidate chromosome-associated virulence-locus configurations in ST11 hv-CRKP that are distinct from canonical fusion-plasmid architectures. This evidence extends the current models beyond plasmid fusion and underscores the value of genomic surveillance strategies capable of detecting chromosomal virulence, which may be overlooked when surveillance focuses solely on virulence plasmids. Defining this evolutionary trajectory provides a foundation for infection prevention and control, as well as for designing targeted interventions to limit the spread of these high-risk pathogens. Using multiple lines of genomic evidence, we established a framework for assessing candidate chromosomal localizations and identifying breakpoint-associated read signatures.