Abstract: OBJECTIVE To explore the distribution and epidemiological characteristics of membrane porin ompK36 variants in Klebsiella pneumoniae causing clinical infection and observe the correlation between the membrane porin ompK36 variants and the virulence factor, drug resistance and clinical characteristics.METHODS Totally 71 strains of K. pneumoniae were clinically isolated from 71 patients who were hospitalized in The Affiliated Hospital of North China Polytechnic University from Aug 2018 to Dec 2018, 30 of which were carbapenem-resistant K. pneumoniae (CRKP), and 41 were carbapenem-sensitive K. pneumoniae (CSKP).The phenotypes of hypermucoviscosity (HM) were detected by means of stringing test, the membrane porin ompK36 variants, common capsular serotypes (K1, K2, K5, K20, K54, K57) and virulence genes(rmpA, wabG, uge, entB, aerobactin, iroN, kfuB) were detected by PCR, the genotypes of the strains were identified with the use of PFGE and MLST, and the drug resistance of the ompK36 types was observed. RESULTS Among the 71 strains of K. pneumoniae with the ompK36 variants, there were 12 (16.9%) strains of type A, 2 (2.8%) strains of type B, 28 (39.4%) strains of type C, 26 (36.6%) strains of type D and 3 (4.2%) untyped strains.There were 23 (76.7%) strains of CRKP carrying with ompK36 D and 27 (65.9%)strains of CSKP carrying with ompK36 C.Totally 29 (40.8%) strains were tested positive for HM phenotypes.The detection rate of capsular serotypes was 35.2% (25 strains), the strains of type K1, K2, K5 and K57 and 1 of 2 (50.0%) K54 strains belonged to type C.There was significant difference in the distribution of ompK36 variants between the rmpA and aerobactin genes(P＜0.05).ST23 (35.7%) was the most common STs among the type C strains, followed by ST86 (17.9%), and all of the type K1 strains belonged to ST23; ST11 (41.9%) was the most common STs among the non-type C strains, followed by ST15 (9.3%).The drug resistance rate of the type D strains to cephalosporins, enzyme inhibitors, carbapenems and quinolones was the highest, while the drug resistance rate of the type C strains was the lowest among the four types. CONCLUSION The K. pneumoniae strains carrying with ompK36 C and D are dominant in the hospital; the HM phenotype, K1/K2 serotypes and virulence genes rmpA and aerobactin are the most common among the strains carrying with ompK36 C, the virulence score of the type C strains is the highest, and the drug resistance rate is the lowest.The drug resistance rate of the type D strains is the highest, ST11 is the predominant PFGE type, the detection of ompK36 variants may facilitate the clinical prediction of the K. pneumoniae virulence strains.