en Epidemiologic Studies Epidemiologic Studies مقاله پژوهشی Original Research Article <span style="font-size:11pt"><span style="line-height:150%"><span style="font-family:Calibri,sans-serif"><b><span style="font-size:12.0pt"><span style="line-height:150%"><span style="font-family:&quot;Times New Roman&quot;,serif">Background and Objective:</span></span></span></b><span style="font-size:12.0pt"><span style="background:white"><span style="line-height:150%"><span style="font-family:&quot;Times New Roman&quot;,serif"><span style="color:black"> Uropathogenic Escherichia coli (UPEC) strains are the primary causative agents of urinary tract infections (UTIs). Molecular characterization of UPEC strains plays a crucial role in infection management, as molecular determinants contribute to antibiotic resistance (AR). </span></span></span></span></span><span style="font-size:12.0pt"><span style="line-height:150%"><span style="font-family:&quot;Times New Roman&quot;,serif">This study aimed to investigate the antibiotic resistance profiles, prevalence of ESBL, integron, and pathogenicity island markers, and the genetic relatedness of UPEC isolates using PFGE.</span></span></span></span></span></span><br> <span style="font-size:11pt"><span style="line-height:150%"><span style="font-family:Calibri,sans-serif"><b><span style="font-size:12.0pt"><span style="line-height:150%"><span style="font-family:&quot;Times New Roman&quot;,serif">Methods:</span></span></span></b><span style="font-size:12.0pt"><span style="line-height:150%"><span style="font-family:&quot;Times New Roman&quot;,serif"> Urine samples were collected from catheterized ICU patients. UPEC isolates were identified by standard biochemical tests. Antimicrobial susceptibility was assessed using the disk diffusion method. Resistance markers (ESBLs, integrons, PAIs) were detected by PCR, and genetic clustering was performed using PFGE with XbaI restriction enzyme.</span></span></span></span></span></span><br> <span style="font-size:11pt"><span style="line-height:150%"><span style="font-family:Calibri,sans-serif"><b><span style="font-size:12.0pt"><span style="line-height:150%"><span style="font-family:&quot;Times New Roman&quot;,serif">Results: </span></span></span></b><span style="font-size:12.0pt"><span style="line-height:150%"><span style="font-family:&quot;Times New Roman&quot;,serif">Of the 50 UPEC isolates, the highest resistance rates were observed against piperacillin (80%), ampicillin (76%), and cotrimoxazole (68%), while imipenem (94%) and amikacin (86%) showed the highest susceptibility. MDR and XDR phenotypes were detected in 62% and 22% of isolates, espectively. PFGE analysis revealed 38 distinct pulsotypes, indicating substantial genetic diversity. Among resistance markers, the most prevalent were PAI-IV536 (80%), PAI-IICFT073 (70%), and Int1 (66%), whereas Int3 was absent in all isolates.&quot;</span></span></span></span></span></span><br> <span style="font-size:11pt"><span style="line-height:150%"><span style="font-family:Calibri,sans-serif"><b><span style="font-size:12.0pt"><span style="line-height:150%"><span style="font-family:&quot;Times New Roman&quot;,serif">Conclusion:</span></span></span></b>&nbsp;<span style="font-size:12.0pt"><span style="line-height:150%"><span style="font-family:&quot;Times New Roman&quot;,serif">The UPEC population studied exhibits high genetic diversity and a notable burden of multidrug resistance. The strong association between integrons (particularly Int1) and resistance phenotypes suggests that horizontal gene transfer is a major driver of antimicrobial resistance dissemination. Continuous molecular surveillance is critical to prevent the spread of these resistant clones in healthcare settings.</span></span></span></span></span></span><br> &nbsp; Molecular Epidemiology, Uropathogenic Escherichia coli, Antibiotics Resistance, Pulsed-Field Gel Electrophoresis 38 38 http://journal.zums.ac.ir/browse.php?a_code=A-10-7546-1&slc_lang=en&sid=1 Elahe Sadat Hajimiri elahehagimiri@yahoo.com 5200319475328460090337 5200319475328460090337 No Department of Microbiology, Zanjan Branch, Islamic Azad University, Zanjan, Iran Reza Shapouri reza.shapouri@iau.ac.ir 5200319475328460090338 5200319475328460090338 Yes Department of Microbiology, Zanjan Branch, Islamic Azad University, Zanjan, Iran Habib Zeighami zeighami@zums.ac.ir 5200319475328460090339 5200319475328460090339 No Department of Microbiology, School of Medicine, Zanjan University of Medical Sciences, Zanjan, Iran Leili Shokoohizadeh l.shokohizadeh@umsha.ac.ir 5200319475328460090340 5200319475328460090340 No Infectious Disease Research Center, Hamadan University of Medical Sciences, Hamadan, Iran