Abstract:ObjectiveTo understand the microbiological and clinical features of bloodstream infection(BSI) with high virulent Klebsiella pneumoniae(hvKP). MethodsThe strains and clinical data of 159 patients with Klebsiella pneumoniae (K. pneumoniae) BSI at the Second Hospital of Dalian Medical University from April 2013 to March 2016 were collected. Statistical analysis was performed using SPSS 19.0 software. Results35.22%(56/159)of patients were with hvKP BSI, K1 and K2 serotypes in hvKP BSI accounted for 51.79% and 26.79% respectively. The main source of hvKP BSI was liver abscess(n=26,46.43%),the classic type of K. pneumoniae (cKP) BSI was primary bacteremia(n=41,39.81%). Difference in different types of infection between two groups of patients was statistically significant(χ2=57.782,P<0.001),89.29% of hvKP BSI was communityassociated infection(CAI), and 73.79% of cKP BSI was healthcareassociated infection(HAI). Difference in underlying diseases between two groups of patients was statistically significant(χ2=36.532,P<0.001),50.00% of hvKP BSI patients had diabetes, 45.63% of cKP BSI patients had malignant tumor. Icidence of septic shock in hvKP BSI patients was higher than that of cKP BSI patients(32.14% vs 8.74%; χ2=14.096,P<0.001). The proportion of ESBLsproducing of hvKP and cKP were 5.36% (3/56)and 47.57%(49/103)respectively,difference was statistically significant(χ2=29.375,P<0.001). Klebsiella pneumoniae carbapemase(KPC)producing hvKP was not found. Resistance rates of hvKP to ceftazidime, ceftriaxone, cefepime, aztreonam, gentamicin, levofloxacin, and compound sulfamethoxazole were all lower than cKP(all P<0.05). ConclusionhvKP BSI is common in CAI, infection sources and underlying diseases are difference from cKP BSI, hvKP BSI is prone to cause septic shock. Both laboratories and clinicians should pay attention to hvKP infection and the change trend of antimicrobial resistance.