Evaluation of the Relative Frequency of Carbapenemase Genes by Phenotypic and Genotypic Methods in Pseudomonas aeruginosa Isolates from Patients with Open Heart Surgery in Iran

Article Type Original Article 1 Department of Microbiology, School of Medicine, Guilan University of Medical Sciences, Rasht, Iran 2 Cardiogenetic Research Center, Rajaei Cardiovascular Medical and Research Center, Iran University of Medical Sciences, Tehran, Iran 3 Urology Research Center, Razi Hospital, School of Medicine, Guilan University of Medical Sciences, Rasht, Iran 4 School of Medicine, Guilan University of Medical Sciences, Rasht, Iran 5 Anatomical and clinical pathologist, Fellowship of dermatopathology, Head of Sina Pathobiology Lab, Yazd, Iran. * Correspondence Department of Microbiology, School of Medicine, Guilan University Campus, 7th Km of Rasht-Tehran Highway, Rasht, Guilan, Iran. E-mail: mojtahedi.a@iums.ac.ir Article History Received: January 06, 2023 Accepted: February 21, 2023 Published: March 10, 2023 Backgrounds: Carbapenem resistance among Pseudomonas aeruginosa strains is alarming. This study aimed to investigate the relative frequency of carbapenem-resistant P. aeruginosa strains by phenotypic and genotypic methods. Materials & Methods: The antibiotic susceptibility pattern of 60 P. aeruginosa isolates was determined by disk diffusion method (Kirby-Bauer). BD Phoenix automated microbiology system was used to identify carbapenem-resistant isolates, and the minimum inhibitory concentration (MIC) was determined using E-Test. In addition, mCIM (modified carbapenem inactivation method) phenotypic test was performed to evaluate carbapenem resistance genes in P. aeruginosa isolates. The prevalence of metallo-beta-lactamase (MβL) genes in carbapenem-resistant P. aeruginosa isolates was determined using conventional polymerase chain reaction (PCR). Findings: The frequency of carbapenem-resistant P. aeruginosa isolates was 36% (22 of 60). The highest resistance was observed to imipenem and meropenem (36.6%), and the highest sensitivity was observed to amikacin (75%). All carbapenem-resistant P. aeruginosa isolates were confirmed by the BD Phoenix automated system (MIC>8 μg/mL for imipenem and meropenem), E-test (MIC ˂ 32 μg/mL), and mCIM assay (the growth inhibition zone diameter was 6-8 mm). In carbapenem-resistant P. aeruginosa isolates, the frequency of blaVIM, blaIMP, and blaSPM genes was 9.1% (2 of 22), 4.5% (1 of 22), and 4.5% (1 of 22), respectively. BlaKPC and blaNDM genes were not found in any of the isolates. Conclusion: Based on the present study results, all phenotypic tests used to identify carbapenemase-producing isolates had the same sensitivity (100%) and specificity (100%). Copyright@ 2023, TMU Press. This open-access article is published under the terms of the Creative Commons Attribution-NonCommercial 4.0 International License which permits Share (copy and redistribute the material in any medium or format) and Adapt (remix, transform, and build upon the material) under the Attribution-NonCommercial terms. 10.52547/iem.9.1.55