Tehran University of Medical Sciences Iranian Journal of Microbiology 2008-3289 18 2 2026 04 26 235 243 EN Sarah Al-Khafaji Department of Microbiology, College of Veterinary Medicine, Al-Muthanna University, Al-Muthanna, Iraq; Department of Biology, College of Science, University of Al-Qadisiya, Al-Qadisiya, Iraq Firas Al-Mayahi Department of Biology, College of Science, University of Al-Qadisiya, Al-Qadisiya, Iraq 2025 09 22 2026 01 29 Background and Objectives: Fluoroquinolones represent a class of antibiotics commonly used to manage Pseudomonas aeruginosa infections. The appearance of fluoroquinolone resistance in P. aeruginosa represents a critical challenge to healthcare systems. Materials and Methods: Between January and December 2024, 650 clinical specimens were collected from Al-Hussein Teaching Hospital and Al-Rumaitha Hospital in Al-Muthanna, Iraq. P. aeruginosa was identified by conventional biochemical assays and confirmed with the Vitek 2® system. Susceptibility testing was performed by disk diffusion. PCR was conducted to detect plasmid-mediated quinolone resistance determinants, namely qnrA, qnrB, qnrD, qnrS, aac(6′)-Ib-cr, and qepA. Results: Among the 650 specimens analyzed, 374 (57.54%) were positive for bacterial culture, with P. aeruginosa representing 40.10% (150/374) of the identified isolates. Among these, 39 (26%) exhibited resistance to at least one fluoroquinolone used. The most frequently detected gene was qnrB (67.65%), followed by qnrD (61.76%), qnrS (55.88%), aac(6')-Ib-cr (47.00%), and qepA (41.17%), while qnrA and qnrC were not detected in any isolate. Conclusion: The fluoroquinolone resistance and widespread occurrence in isolates of P. aeruginosa from Al-Muthanna Province pose a challenge to infection management, as mobile genetic elements facilitate the rapid dissemination of resistance and limit available therapeutic options, emphasizing the necessity for genetic monitoring and effective antibiotic management. https://ijm.tums.ac.ir/index.php/ijm/article/view/5802 https://ijm.tums.ac.ir/index.php/ijm/article/download/5802/1881