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Beikzadeh B, Gerami M, Azizi M, Mozayyan Esfahani H, Rostami S. Investigating Immune Evasion Genes Expression and Biofilm Formation of Klebsiella pneumoniae Isolates From Patients With Ventilator-associated Pneumonia. Res Mol Med (RMM) 2025; 13 (3) :165-176
URL: http://rmm.mazums.ac.ir/article-1-612-fa.html

Background: Klebsiella pneumoniae, a leading opportunistic pathogen, exhibits increasing multidrug resistance (MDR) and biofilm formation, posing significant challenges in hospital environments, especially in developing regions, such as Iran. This study aimed to characterize the antibiotic resistance profiles, biofilm-formation capacity, and expression levels of immune evasion genes (fimH-1, mrkD, traT) in K. pneumoniae isolates from patients with ventilator-associated pneumonia.
Materials and Methods: A total of K. pneumoniae isolates were obtained from sputum samples of patients with ventilator-associated pneumonia. Antibiotic susceptibility was determined using the Kirby-Bauer disk diffusion method. Biofilm formation was quantified by a crystal violet assay. The presence and expression of immune evasion genes were evaluated by polymerase chain reaction (PCR) and quantitative real-time PCR, respectively.
Results: High resistance rates were observed: 100% to ampicillin-sulbactam, 96.66% to ciprofloxacin, 93.33% to cefepime, and 83.33% to imipenem. About 50% of isolates were strong biofilm formers, 33.3% moderate, and 16.7% weak. mrkD and fimH-1 genes were detected in 100% and 96.66% of isolates, respectively, while traT was present in 30%. Gene expression analysis revealed significant upregulation of fimH-1 (P=0.005) and mrkD (P<0.0001), while traT expression showed no significant change (P=0.2803). No significant correlation was found between the prevalence of immune evasion genes and biofilm production (P>0.05).
Conclusion: This study highlights a high prevalence of multidrug-resistant (MDR) K. pneumoniae isolates with strong biofilm formation and upregulated immune evasion genes among patients with ventilator-associated pneumonia. The significant upregulation of fimH-1 and mrkD suggests enhanced adaptation for persistence in the face of host defenses. These findings underscore the urgent need for targeted interventions to control K. pneumoniae infections amid the growing threat of antibiotic resistance.