Background and Aim: Klebsiella pneumoniae (K. Pneumoniae) is one of the prevalent infectious bacteria, especially in hospitalized patients. Recently, its' multi drug resistance (MDR) trait has become more important and regarded as a virulant factor. In this study, we evaluated bla-ctx-m-type gene in clinical isolates of K.pneumoniae with multi drug resistance.

 Materials and Methods: In this descriptive cross-sectional study, a total of 280 K.pneumoniae strains were isolated from patients. Initially, we evaluated drug sensitivity with disk diffusion method. Then the minimum inhibitory concentration (MIC) of resistant isolates was determined with E-test stripes. The existence of ESBL (Extended Spectrum Beta-Lactamase) enzymes was identified by ESBL disks in Double Disk method. These resistances were evaluated with PCR. Finally, results were analyzed by SPSS software. Results: From total 280 K.pneumoniae, 62 samples (22.14%) showed multi drug resistance trait. 40 strains of these MDR isolates were completely resistant to the experimental cephalosporins, and positive in ESBL production by Double Disk methodology. These results were proved and evaluated with PCR and Sequencing.

  Conclusion: Detection of 22.14% MDR trait, especially extended spectrum beta-lactamases in resistant clinical K.pneumoniae isolates, points to the in usage of extended spectrum cephalosporins.