OBJECTIVE To analyze the hypermucoviscous Klebsiella pneumoniae （HMKP） isolated from the intensive care unit （ICU） through whole-genome sequencing （WGS） technology, thereby understanding its etiology and genomic characteristics.
METHODS A total of 31 strains of HMKP confirmed by identification and the string test （≥5 mm） were collected for antimicrobial susceptibility testing. WGS was employed to analyze the multi-locus sequence typing （MLST）, K serotype, antimicrobial resistance genes and virulence factors of the strains. Hypervirulent K. pneumoniae （hvKP） were verified.
RESULTS The average age of patients infected with HMKP was （64.55 ± 11.31） years, and the specimens mainly originated from blood （n=13） and pus （n=11）. Invasive infections, such as liver abscesses, were the main clinical manifestations. Three strains were carbapenem-resistant HMKP （CR-HMKP）, and the rest were sensitive to most antimicrobial agents. WGS identified 17 STs, predominantly ST23 （32.26%）, with K1 （35.48%） and K2 （29.03%） being the main K serotypes. MLST cluster analysis showed that hvKP had high homology.Among the resistance genes, SHV had the highest detection rate （93.55%）, and carbapenemase genes involved KPC-18 and OXA-232. Except for rmpA2 （22.58%）, the detection rates of other virulence genes （such as iutA, entB） were all ＞80%. A total of 27 hvKP strains were identified, and the results of WGS and PCR were highly consistent.
CONCLUSIONS The HMKP strains isolated from the ICU exhibited marked invasive and hypervirulent traits, with K1/K2 as the predominant serotypes and ST23 as the predominant sequence type. The emergence of CR-HMKP signals the convergence of resistance and high virulence, urging enhanced infection surveillance and control in the ICU.
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