Molecular Characterization of Beta-Lactamase-Encoding Genes and Associated Antimicrobial Resistance in Clinical Isolates of Klebsiella pneumoniae from Zanjan, Iran
Volume 11, Issue 2, Spring 2026, Pages 874-883
https://doi.org/10.30491/hpr.2026.588535.1541
Zahra Jafari, Reza Shapoury, Habib Zeighami, Leili Shokoohizadeh
Abstract 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.