[Study on transmission characteristics and genetic variation of carbapenem-resistant <i>Klebsiella pneumonia</i> based on whole genome sequencing].

<b>Objective:</b> To analyze the short-term hospital-based transmission characteristics and gene variation of Carbapenem-Resistant <i>Klebsiella pneumoniae</i> (CRKP) by genome-wide technique to provide evidence for transmission control. <b>Methods:</b> The experimental strain was derived from all the CRKP isolated in Affiliated Hospital of North China University of Science and Technology from October 2022 to December 2023. Strain identification and drug susceptibility were tested with VITEK 2-Compact automatic bacterial identification drug susceptibility analyzer or disk method, and the results were interpreted through whole genome sequencing. The ST type, carbapenem resistance gene, virulence factor, and O serotype of the collected strains were analyzed. <b>Results:</b> Among the 115 strains of CRKP, 94 strains were isolated from the intensive care unit (ICU), accounting for 81.7%, and 21 strains were isolated from the non-intensive care unit (NICU), accounting for 18.3%. The 115 strains of CRKP can be divided into 11 ST types, of which ST11 type was the most (54.8%, 63/115), followed by ST15 type (22.6%, 26/115) and ST5492 type (15.7%, 18/115). Type ST5492 was a new clonal group in the region. The 115 strains of CRKP could be divided into 7 O serotypes, most of which were O2a type(32.2%,37/115), followed by O5 type(30.4%,35/115) and O1 type(27.8%,32/115). The resistance genes of carbapenem antibiotics showed that there were 107 strains carrying the <i>bla</i>_KPC-2 gene, one strain with the <i>bla</i>_NDM-1 gene, and one strain with both the <i>bla</i>_KPC-2 and <i>bla</i>_NDM-13 genes. Virulence genes were detected in 55 CRKP strains (47.8%, 55/115), among which six strains detected <i>peg-344</i>, <i>iucA, iroB, rmpA,</i> and <i>rmpA2</i> virulence genes (5.2%, 6/115). Four virulence genes (<i>peg-344, iucA, rmpA,</i> and <i>rmpA2</i>) were detected in 34 strains (29.6%, 34/115). Three virulence genes (<i>iucA, iroB</i> and <i>rmpA</i>) were detected in two strains (1.7%, 2/115). Three virulence genes (<i>peg-344, iucA</i> and <i>rmpA</i>) were detected in one strain (0.8%, 1/115). <i>IucA</i> and <i>rmpA</i> virulence genes were detected in 12 strains (10.4%, 12/115). KPC-2_ST11_O2a, KPC-2_ST15_O1 and KPC-2_ST5492_O5 were dominant clones, and their distribution was mainly in the intensive care unit. The whole genome sequence analysis showed that there were three dominant clones, among which ST11 clones were subdivided into three dominant O serotypes, all of which were mainly in the intensive care unit. <b>Conclusion:</b> The popular strain in the hospital of CRKP is a KPC-2_ST11 clone group carrying iucA, rmpA/rmpA2, with cross-department transmission and mutation. ST5492 is a newly-launched clone type. The intensive care unit of hvKP carrying five virulence genes, including peg-344, should be alert to the epidemic risk of CR-hvKP outbreak.