Tehran University of Medical Sciences Iranian Journal of Microbiology 2008-3289 16 1 2024 02 12 39 48 Hamed Hatami Mirbag Department of Microbiology and Parasitology, School of Medicine, Bushehr University of Medical Sciences, Bushehr, Iran; Student Research Committee, Bushehr University of Medical Sciences, Bushehr, Iran Saeed Tajbakhsh Department of Microbiology and Parasitology, School of Medicine, Bushehr University of Medical Sciences, Bushehr, Iran; The Persian Gulf Marine Biotechnology Research Center, The Persian Gulf Biomedical Sciences, Research Institute, Bushehr University of Medical Sciences, Bushehr, Iran Azam Askari Department of Microbiology and Parasitology, School of Medicine, Bushehr University of Medical Sciences, Bushehr, Iran Forough Yousefi Department of Microbiology and Parasitology, School of Medicine, Bushehr University of Medical Sciences, Bushehr, Iran; The Persian Gulf Marine Biotechnology Research Center, The Persian Gulf Biomedical Sciences, Research Institute, Bushehr University of Medical Sciences, Bushehr, Iran 2023 10 02 2023 12 29 Background and Objectives: Klebsiella pneumoniae is an opportunistic pathogen responsible for causing nosocomial and community-acquired infections. Its pathogenicity is associated with a variety of virulence factors and antibiotic resistance. The aim of the present study was to compare virulence attributes between ESBL and non-ESBL producing isolates. Materials and Methods: A total of 113 K. pneumoniae including 56 ESBL and 57 non ESBL-producers were collected in Bushehr province, Iran, from November 2017 to February 2019. Enzymatic profile, hypermucoviscosity and biofilm formation were investigated phenotypically. In addition, the presence of rmpA, aerobactin, kfu, allS, mrkD, ybtS, entB, iutA, fimH, wabG, wcaG, K1 and K2 genes were detected by PCR and sequencing. Results: There was no statistically significant difference in enzymatic profile between ESBL and non-ESBL producers. The prevalence of the hypermocoviscosity was lower among ESBL compared to non-ESBL producers but the intensity of biofilm was higher in the ESBL producers. Among the virulence genes, K1, rmpA, iutA, and aero were observed only in non-ESBLs. Moreover, the carriage of allS, K, K2, rmpA, iutA and aero genes was higher in hypermucoviscous in comparison with non hypermucoviscous isolates. Conclusion: The identification of potentially pathogenic isolates plays an important role in preventing their spread as well as the success of their treatment. https://ijm.tums.ac.ir/index.php/ijm/article/view/4428 https://ijm.tums.ac.ir/index.php/ijm/article/download/4428/1635