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Background & aim: Klebsiella pneumonia, is the most significant member of the enterobacteiaceae, which is one of the most important pathogen involved in health care associate infections. The capsular polysaccharide is a prominent virulence factor in the pathogenesis of this organism and serotypes K1and K2 are the most virulent types in human infections. The main aims of this study were to assess the antimicrobial susceptibility and to determine the distribution of serotypes K1, K2 by detecting of wzc and orf10 genes in clinical isolates of K. pneumoniae.
 
Methods: In the present cross-sectional study, a total number of 149 clinical isolates of K. pneumoniae were collected from patients admitted to educational hospitals of Qazvin. Bacterial identification was performed by standard laboratory methods. Antimicrobial susceptibility was determined by standard Kirby–Bauer disk diffusion method according to the Clinical Laboratory Standards Institute (CLSI) guideline. PCR assay was further performed for the detection of wzc and orf10 genes related to serotypes K1 and K2, respectively. The data were analyzed by using descriptive statistics and chi-square.
 
Results: totally, 98 (65.8%) of isolates showed multidrug resistance (MDR) pattern among those ceftazidime (61.8%) and cefotaxime (60.4%) showed the highest rates of resistance whereas amikacin and ciprofloxacin revealed high susceptibility rates as 91.3% and 59.1%, respectively. Results of the PCR assay showed that 79 (53%) isolates related to K1serotype, 19 (12%) to K2 serotype and 51 (34%) of isolates were belonged to non K1/ K2 serotypes. no significant association was seen between serotypes K1, K2 and MDR pattern (P< 0.05).
 
Conclusion: the present study indicated considerable rate of serotypes K1, K2 with MDR pattern among clinical isolates of K. pneumoniae collected from Qazvin hospitals. Considering the major role of these serotypes with high rates of drug resistance in different clinical infections, using of appropriate infection control measures and treatment strategies are essential to prevent further dissemination of these virulent and resistant isolates in studied hospitals.