AUTHOR=Zhang Fushan , Li Leyuan , Zhao Yuxin , Dong Huiyue , Zhao Buhui , Zhao Xiaoyu , Xia Ziwei , Chi Leizi , Wang Yan , Li Ruichao , Qin Shangshang , Fu Xiangjing 

TITLE=Molecular characterization of hybrid virulence plasmids in ST11-KL64 KPC-2-producing multidrug-resistant hypervirulent Klebsiella pneumoniae from China

JOURNAL=Frontiers in Microbiology

VOLUME=15

YEAR=2024

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2024.1353849

DOI=10.3389/fmicb.2024.1353849

ISSN=1664-302X

ABSTRACT=<sec><title>Introduction</title><p>Carbapenem-resistant hypervirulent <italic>Klebsiella pneumoniae</italic> (CR-HvKP) strains combining virulence and multidrug resistance (MDR) features pose a great public health concern. The aim of this study is to explore the evolutionary characteristics of virulence in CR-HvKP by investigating the genetic features of resistance and virulence hybrid plasmids.</p></sec><sec><title>Methods</title><p>The resistance and virulence phenotypes were determined by using antimicrobial susceptibility testing and the mouse bacteremia infection model, respectively. Plasmid profiles were investigated by S1 nuclease pulsed-field gel electrophoresis (S1-PFGE) and Southern blotting, conjugation assay, and whole genome sequencing (WGS). Bioinformatics tools were used to uncover the genetic features of the resistance and virulence hybrid plasmids.</p></sec><sec><title>Results</title><p>Two ST11-KL64 CRKP clinical isolates (KP18-3-8 and KP18-2079), which exhibited enhanced virulence compared with the classic CRKP, were detected positive for <italic>bla</italic><sub>KPC−2</sub> and <italic>rmpA2</italic>. The virulence level of the hypermucoviscous strain KP18-3-8 was higher than that of KP18-2079. S1-PFGE, Southern hybridization and WGS analysis identified two novel hybrid virulence plasmids in KP18-3-8 (pKP1838-KPC-vir, 228,158 bp) and KP18-2079 (pKP1838-KPC-vir, 182,326 bp), respectively. The IncHI1B/repB-type plasmid pKP1838-KPC-vir co-harboring <italic>bla</italic><sub>KPC−2</sub> and virulence genes (<italic>rmpA2, iucABCD</italic> and <italic>iut</italic>A) but lacking type IV secretion system could transfer into non-hypervirulent ST11 <italic>K. pneumoniae</italic> with the assistance of a helper plasmid in conjugation. The IncFII/IncR-type virulence plasmid pKP18-2079-vir may have been generated as a result of recombination between a typical pLVPK-like virulence plasmid and an MDR plasmid.</p></sec><sec><title>Conclusion</title><p>Our studies further highlight co-evolution of the virulence and resistance plasmids in ST11-CRKP isolates. Close surveillance of such hybrid virulence plasmids in clinical <italic>K. pneumoniae</italic> should be performed.</p></sec>