Baqiyatallah University of Medical Sciences Hospital Practices and Research 2476-390X 11 2 2026 06 01 Molecular Characterization of Beta-Lactamase-Encoding Genes and Associated Antimicrobial Resistance in Clinical Isolates of Klebsiella pneumoniae from Zanjan, Iran 874 883 248293 10.30491/hpr.2026.588535.1541 EN Zahra Jafari Department of Microbiology, Za.c., Islamic Azad University, Zanjan, Iran Reza Shapoury Department of Microbiology, Za.c., Islamic Azad University, Zanjan, Iran 0000-0003-1998-759X Habib Zeighami Department of Medical Microbiology, School of Medicine, Zanjan University of Medical Sciences, Zanjan, Iran Leili Shokoohizadeh Department of Microbiology, School of Medicine, Hamadan University of Medical Sciences, Hamadan, Iran Journal Article 2026 05 02 Background: Klebsiella pneumoniae (K. pneumoniae) is a major cause of hospital-acquired infections, where treatment options are restricted due to drug-resistant strains, including those producing extended-spectrum beta-lactamases (ESBLs) and carbapenemases. Objectives: This study focuses on the molecular identification of beta-lactamase and carbapenemase genes in K. pneumoniae strains from Valiasr Hospital, Zanjan, to enhance infection control and antimicrobial strategies. Methods: In this cross-sectional study, 50 K. pneumoniae clinical isolates were obtained from blood, urine, and wound samples of ICU patients in 2024. Phenotypic identification and antimicrobial susceptibility testing were performed using the Kirby-Bauer disk diffusion method. Genomic DNA extraction was performed using the phenol-chloroform method, followed by polymerase chain reaction (PCR) to identify resistance genes (blaCTX-M, blaTEM, blaSHV, blaIMP, blaVIM). The PCR products were analyzed via agarose gel electrophoresis, with data processed using SPSS version 26. Results: The mean age of the patients was 58.90 years, and the isolates exhibited high resistance rates to ampicillin (90%), piperacillin (78%), and cefotaxime (72%). Genotypic testing indicated ESBL gene frequencies: blaTEM (46%), blaSHV (44%), and blaCTX-M (40%), along with carbapenemase genes blaVIM and blaIMP in 26% and 22% of isolates, respectively. A significant link was found between the blaTEM gene and urinary isolates (P = 0.037). Furthermore, the presence of the blaTEM, blaSHV, and blaCTX-M genes was associated with MDR, XDR, and PDR phenotypes (P < 0.05), with 100% of MDR isolates containing all three genes. Conclusion: The study found a high prevalence of ESBL genes linked to multidrug resistance patterns among K. pneumoniae isolates in ICUs. The presence of carbapenemase genes (blaIMP and blaVIM) indicates a shift toward carbapenem resistance, underscoring the urgent need for better antibiotic surveillance and infection control in these settings.

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