Genome sequence of a ST65 hypervirulent Klebsiella pneumoniae isolate carrying mcr-8 from China.

Objectives: In this study, we report the complete genome sequence of a ST65 hypervirulent Klebsiella pneumoniae isolate carrying mcr-8 from China. The aim was to investigate its molecular characteristics and resistant mechanism.

Methods: A colistin-resistant hvKP was isolated from an inpatient in China. The whole genome was sequenced on Illumina NovaSeq 6000 and long-read ONT platforms. de novo assembly was conducted using SPAdes and Unicycler. S1 nuclease pulsed-field gel electrophoresis, Southern-blot, and antimicrobial susceptibility testing were performed. Sequence type, antimicrobial resistance and virulence-related genes were predicted from the sequence. The circular maps of multiple plasmids comparisons were drawn by the BLAST Ring Image.

Results: The complete genome sequence of K. pneumoniae ACESH00926 consists of one chromosome and two plasmids. ACESH00926 belongs to K2 ST65 according to the MLST scheme. ACESH00926 showed high resistance to colistin (MIC > 8 µg/mL). Several ARGs were identified, including mobile colistin-resistant gene mcr-8 which was located in an IncFIl(K)/IncFIA(HI1) type plasmid. The bigger plasmid was a pK244-like virulence plasmid. It carrying a series of virulence genes, such as the regulator of the mucoid phenotype (rmpA and rmpA2), salmochelin siderophore biosynthesis (iroB), ABC transporter (iroC), ferric aerobactin receptor (iutA), aerobactin siderophore biosynthesis protein (iucC), and aerobactin synthetase (iucA) encoded genes. And another plasmid carrying mcr-8 with a conserved genetic context (dgkA-sasA-copR-mcr-8-ccdA-ccdB-xerD-repE-parM-umuC-lexA-klcA).

Conclusions: It is necessary to emphasize the necessity of monitoring a combination of colistin-resistant and hypervirulent Klebsiella pneumoniae strains in the future.