Abstract: Objective To delineate the clinical presentations, microbiological profiles, and molecular epidemiology of liver abscess induced by Klebsiella pneumoniae. Methods Between June 2020 and October 2022, 67 patients diagnosed with Klebsiella pneumoniae liver abscess(KPLA) were enrolled in our hospital, with clinical data and laboratory findings being systematically collected. The virulence attributes, antimicrobial resistacet profiles, and genetic diversity of the K. pneumoniae strains were comprehensively analyzed. Characterized by their high mucoviscosity phenotypes, these isolates had their virulence factors identified via polymerase chain reaction (PCR), their resistance patterns determined through antimicrobial susceptibility testing, and their clonal distribution ascertained by multilocus sequence typing(MLST). Results In 27 of 67(40.3%) isolates of K. pneumoniae, hypermucoviscosity was observed, indicating the presence of hypermucoviscous K. pneumoniae(hvKP). Infections associated with hypermucoviscous strains were found to be more likely to develop bacteremia compared to infections caused by classic K. pneumoniae strains. Similarly, infections associated with hypermucoiscous strains were more frequently associated with hepatobiliary diseases than those without hepatobiliary diseases. The rmpA and aerobactin genes were present in 44.5% and 37.1% of the isolates, respectivelly, while serotypes K1 and K2 were identified in 44.5% and 33.4% of the hypermucoviscous strains, respectively. A significant association was identified between strains carrying the rmpA and aerobactin genes and the hypermucoviscous phenotype. Through multilocus sequence typing analysis, 10 different sequence types were identified among the 67 strians of K. pneumoniae. Conclusion In the present study, a high prevalence of hvKp strains in KPLA was reported. Liver abscess caused by hvKP were found to be associated with diabetes, hepatobiliary disease, and an increased likelihood of leading to bacteremia. The rpmA gene was identified as the main virulence factor in hvKP liver abscess. It is emphasized that for patients suffering from hvKP liver abscess, the identification of occult lesions warrants careful attention. Considering the diverse clinical presentations and the destructive pathogenicity of such isolates, the determination of their comprehensive characteristics is deemed highly essential. Such knowledge is crucial to effectively undertake optimal management and treatment strategies for KPLA.

Key words: Klebsiella pneumoniae, Liver abscess, Clinical characteristics, Virulence factors, Sequence type