〔Abstract〕 Objective To analyze the distribution of virulence genes and drug resistance ofKlebsiella pneumoniae(KP), and to study the correlation between the difference of TLR4 expression in serum and cell levels of patients infected with hypervirulentK.pneumoniae(hvKP) and classicalK.pneumoniae(cKP) and clinical prognosis. Methods The strains and serum of patients with KP were collected, the virulence genes were detected by PCR amplification, and the drug susceptibility was detected; Strains were divided into the hvKP group and cKP group. The expression level of TLR4 in serum was detected by ELISA. A549 human alveolar epithelial cells were infected with hvKP and cKP. The expression of TLR4 was determined by quantitative PCR. Results The derection rates of kfu, rmpA1 and rmpA2 in virulence genes of hvKP group were the highest, reaching 100%, 87.8% and 80.5% respectively. The serum TLR4 level was significantly higher in the hvKP groups than that in the control and cKP groups, which was positively correlated with PSI score and CURB-65 score about clinical prognosis. The expression of TLR4 mRNA was significantly higher in the hvKP groups than that in the control and cKP groups. Conclusion The combination of rmpA1, rmpA2 and magAgenes has higher accuracy in diagnosing hvKP infection. Higher expression of TLR4 in serum and cells induced by hvKP infectiong, and TLR4 level positively correlated with the clinical severity of infected KP, suggesting that TLR4 may be involved in the pathophysiological process of hvkp infection. Serum TLR4 can be used as an detection index for the diagnosis and prognosis of patients with KPN, especially patients with hvkp infection.