Tehran University of Medical Sciences Acta Medica Iranica 0044-6025 59 8 2021 09 22 472 476 Ali Badamchi Children's Medical Center Hospital, Tehran University of Medical Sciences, Tehran, Iran Alireza Namazi Shabestari Department of Geriatric Medicine, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran Mohammad Reza Etemadi Modern Virology Laboratory (Diagnostic), Tehran, Iran Azardokht Tabatabaei Research Center of Pediatric Infectious Diseases, Rasool Akram Hospital, Iran University of Medical Sciences, Tehran, Iran 2020 01 26 2021 06 02 The growth rate of the population aging is increasing worldwide. To assess antimicrobial susceptibility of extended-spectrum β-lactamase- (ESBL-) producing Klebsiella pneumoniae Isolated from Patients aging in Rasool Akram, Hospital, as well as to identify AmpC genes. 100 K. pneumoniae strain isolated from different clinical samples. Isolates resistant to oxyimino-cephalosporins and to cefoxitin evaluated to phenotypic ESBL production and to phenotypic AmpC production, respectively. Detection of resistance genes was then performed using primers specific for AmpC genes. Piperacillin/tazobactam and carbapenems remained the active β-lactam antibiotic against K. pneumoniae. ESBLs were detected among 40 (40%) of K. pneumoniae isolates. CMY-1 gene was detected in 34.3% of all AmpC-positive isolates, whereas CMY-2 and FOX genes were 14.2% and 28.6%, respectively. The consumption of Carbapenem family drugs is high in Iranian hospitals which are used as a first line of treatment without antibiotic susceptibility testing. Therefore, increase in antibiotic resistance to this family drugs is unavoidable in the near future. Therefore, it is necessary to take the necessary measures to modify the administration and use of antibiotics. https://acta.tums.ac.ir/index.php/acta/article/view/8298