Abstract
PURPOSE: Hypervirulent Klebsiella pneumoniae (hvKP) is emerging globally and can cause various infections. This study aimed to investigate the clinical and microbiological characteristics of bloodstream infection (BSI) caused by hvKP. PATIENTS AND METHODS: The clinical data of hospitalized patients with K. pneumoniae BSI were retrospectively analyzed. The K. pneumoniae strains were collected and re-identified, and antimicrobial susceptibility testing was performed using the broth microdilution method. Capsular serotypes and virulence genes were detected using polymerase chain reaction, and hvKP was defined as aerobactin positive. Molecular typing was done by multilocus sequence typing. The hvKP and classic K. pneumoniae (cKP) subgroups were compared. RESULTS: Of the 66 nonrepetitive BSI K. pneumoniae strains included, 29 (43.9%) were hvKP. In these BSI hvKP strains, salmochelin and yersiniabactin accounted for 86.2% and 72.4%, respectively. The prevalence of rmpA, iroBCD cluster, ybtS, clbA, and allS was 89.7%, 86.2%, 72.4%, 51.7%, and 41.4%, respectively, which were all significantly different between the hvKP and cKP subgroups. Serotypes K1 and K2 were strongly associated with hypervirulence (P < 0.05). Nineteen sequence types were scattered in the 29 hvKP strains, and the most common was ST23 (24.1%). None of the hvKP strains were carbapenem resistant. Compared with cKP, hvKP was more capable of developing a liver abscess. However, the 30-day mortality rate was lower (13.8% vs 21.6%) in the hvKP subgroup than in the cKP subgroup. CONCLUSION: This study demonstrated a high proportion of hvKP in BSI K. pneumoniae, most of which were RmpA and siderophore producing, and of multiclonal origin.