Expression of blaSHV in Beta-Lactam-Resistant Pseudomonas aeruginosa Clinical Isolates from Mashhad

Raeisianzadeh, Mona; Karbaschian, Elnaz; Algburi, Ammar; Kohansal, Fatemeh

doi:10.22034/ibhf.2026.575761.1048

Expression of bla_SHV in Beta-Lactam-Resistant Pseudomonas aeruginosa Clinical Isolates from Mashhad

نوع مقاله : مقاله پژوهشی

نویسندگان

Mona Raeisianzadeh ¹

Elnaz Karbaschian ²

Ammar Algburi ³

Fatemeh Kohansal ⁴

¹ Department of Biology, Kavian Institute of Higher Education, Mashhad,Iran

² Department of Animal Science, Faculty of Agriculture, Ferdowsi University of Mashhad, Mashhad, Iran

³ PhD in Microbiology Department of Microbiology, College of Veterinary Medicine University of Diyala Iraq

⁴ Facutly of Science, Islamic Azad University, Mashhad,Iran

10.22034/ibhf.2026.575761.1048

چکیده

The role of bla_SHV expression in beta‑lactam resistance among clinical isolates of Pseudomonas aeruginosa is not fully understood. This study aimed to investigate the expression level of the bla_SHV gene in beta‑lactam‑resistant P. aeruginosa clinical isolates obtained from hospitals in Mashhad. In this cross‑sectional study, 103 clinical isolates of P. aeruginosa were recovered from different hospital wards and clinical specimens. Antimicrobial susceptibility testing was performed against several β‑lactam antibiotics, including third‑ and fourth‑generation cephalosporins. Based on beta‑lactam resistance profiles, particularly resistance to cephalosporins, 20 representative isolates were selected for analysis of bla_SHV gene expression using real‑time quantitative PCR (RT‑qPCR). Total RNA was extracted, converted to cDNA, and gene expression levels were normalized to the 16S rRNA reference gene. Relative expression was calculated using the 2⁻ΔΔCt method with P. aeruginosa PAO1 as the calibrator strain. Statistical analysis was performed to compare expression levels with the reference strain. High resistance rates to several cephalosporins were observed among the isolates, including ceftriaxone (100%), ceftiofur (93.2%), ceftazidime (69%), and cefepime (68.2%). All analyzed isolates showed a significant upregulation of bla_SHV expression compared with the PAO1 reference strain (p < 0.05). Increased bla_SHV expression was also detected in some imipenem‑susceptible isolates, suggesting that transcriptional upregulation of this gene is not directly associated with carbapenem resistance. Upregulation of bla_SHV is associated with resistance to extended‑spectrum cephalosporins in beta‑lactam‑resistant P. aeruginosa clinical isolates from Mashhad. Further studies are required to clarify the clinical implications of bla_SHV overexpression and its contribution to beta‑lactam resistance mechanisms.

کلیدواژه‌ها

Antimicrobial resistance

Gene expression

Hospital infections

RT‑qPCR

موضوعات