Deciphering the Epidemiological Characteristics and Molecular Features of - or -Positive Isolates in a Newly Established Hospital.

The emergence of hypervirulent carbapenem-resistant (hv-CRKP) was regarded as an emerging threat in clinical settings. Here, we investigated the prevalence of CRKP strains among inpatients in a new hospital over 1 year since its inception with various techniques, and carried out a WGS-based phylogenetic study to dissect the genomic background of these isolates. The genomes of three representative -positive strains and the plasmids of four -positive strains were selected for Nanopore long-read sequencing to resolve the complicated MDR structures. Thirty-five CRKP strains were identified from 193 isolates, among which 30 strains (85.7%) harbored , whereas the remaining five strains (14.3%) were positive for . The antimicrobial resistance profiles of -positive isolates were narrower than that of -positive isolates. Five isolates including two -positive isolates and three -positive strains could successfully transfer the carbapenem resistance phenotype by conjugation. All CRKP strains were categorized into six known multilocus sequence types, with ST11 being the most prevalent type. Phylogenetic analysis demonstrated that the clonal spread of ST11 -positive isolates and local polyclonal spread of -positive isolates have existed in the hospital. The gene was located on IncX3, IncFIB/IncHI1B, and IncHI5-like plasmids, of which IncFIB/IncHI1B plasmid has a novel structure. By contrast, all ST11 isolates shared the similar -bearing plasmid backbone, and 11 of them possessed pLVPK-like plasmids. In addition, virulome analysis, larvae infection assay, and siderophore secretion revealed the hypervirulence potential of most -positive strains. Given that these isolates also had remarkable environmental adaptability, targeted measures should be implemented to prevent the grave consequences caused by hv-CRKP strains in nosocomial settings.