Correlation Between Virulence Of Klebsiella Pneumoniae And Expression Of Toll-like Receptor 4 In Alveolar Epithelial Cells And Clinical Analysis

Background: Klebsiella pneumoniae（KP）is the most common gram negative bacteria in community and hospital infection.In recent years,the incidence rate and mortality rate of hypervirulent K.pneumoniae（hv KP）have been increasing.Lung epithelial cells have complex defense mechanisms against invading pathogens.The expression of Toll like receptors（TLRs）can induce and activate the antibacterial pathway of lung epithelium and airway inflammatory response.The results showed that the content of TLR4 in human lung epithelial cells increased after KP infection,but whether the expression of TLR4 is associated with KP typing and virulence genes,and the correlation between TLR4 level and prognosis is unclear.Objective: To analyze the distribution of virulence genes and drug resistance of Klebsiella pneumoniae（KP）.To study Expression of Toll like receptor 4（TLR4）in cell levels infected with the different types of KP,including hvkp,ceftazidime-sensitive K.pneumoniae（CSKP）and carbapenem-resistant K.pneumoniae（CRKP）,and correlation between serum TLR4 and clinical prognosis in pneumonia patients.Methods: Human alveolar epithelial cells A549 were infected by hvkp,CSKP and CRKP strains respectively.The m RNA expression levels of TLR4,TLR2 and downstream h BD2 were detected by q RTPCR.The strains and sera of patients with Klebsiella pneumoniae pneumonia（KPN）were collected to detect the virulence genes and the sensitivity to common clinical antibiotics;According to the virulence gene test results,the collected clinical strains were divided into hvkp group and c KP group.The expression level of TLR4 in patients’ serum was detected by ELISA,and the difference of TLR4 expression in each group and its correlation with patients’ clinical pneumonia score index were compared.Conclusion: The expression of TLR4 in serum and cell levels is positively correlated with the virulence of KP and the clinical prognosis score of KPN,suggesting that TLR4 is involved in the pathophysiological process of hvkp infection.The level of serum TLR4 may be used as an index for the diagnosis and prognosis of patients with KPN,especially patients with hvkp infection.