Iman Hosseinpour - Department of Microbiology, Gorgan Branch, Islamic Azad University, Gorgan, Iran
Leila Fozouni - Department of Microbiology, Gorgan Branch, Islamic Azad University, Gorgan, Iran
Morteza Khademi - Department of Microbiology, Gorgan Branch, Islamic Azad University, Gorgan, Iran
Mehdi Movaghari - Department of Microbiology, Gorgan Branch, Islamic Azad University, Gorgan, Iran
Mohammad Mehdi Akhoondi - Department of Microbiology, Gorgan Branch, Islamic Azad University, Gorgan, Iran

Introduction: The widespread use of antibiotics has contributed to the dissemination of multidrug-resistant pathogens. This study aimed to assess the prevalence of Escherichia coli strains associated with urinary tract infections, characterized by diverse drug-resistance phenotypes. Additionally, the antibacterial properties of gold nanoparticles were examined against each phenotype to determine their effectiveness. Methods: This cross-sectional study was conducted on ۱۷۰ E. coli strains isolated from ۲۵۰ urine samples collected from symptomatic and asymptomatic patients with urinary tract infections (UTIs) between August ۲۰۲۲ and July ۲۰۲۳. The antibiotic susceptibility profiles across various classes of antibiotics were determined using the Kirby-Bauer method. At the same time, the minimum inhibitory concentrations of gold nanoparticles were assessed through the microdilution broth test. Results: Among E. coli isolates, ۹۱ (۵۳.۵۳%), ۴۵ (۲۶.۴۷%), and ۱۷ (۱۰%) isolates were identified as multidrug-resistant (MDR), extensively drug-resistant (XDR), and pandrug-resistant (PDR), respectively. The MIC of gold nanoparticles that inhibited the growth of ۹۰% of PDR isolates (MIC۹۰=۲۰۰ ppm) was two times higher than the MIC۹۰ against XDR isolates (MIC۹۰=۱۰۰ ppm) and four times higher than the MIC۹۰ against MDR isolates (MIC۹۰=۵۰ ppm). There was also a significant difference between the MIC۹۰ and the MIC of gold nanoparticles that inhibited the growth of ۵۰% of PDR and XDR bacteria (P<۰.۰۵). Conclusion: The emergence of MDR, XDR, and PDR uropathogenic E. coli isolates represents a significant societal health concern. Considering the favorable in vitro antimicrobial potential of gold nanoparticles against uropathogenic E. coli isolates, it is recommended to further analyze their applicability as antibiotic alternatives by conducting in vivo studies.

Escherichia coli, Gold nanoparticles, Drug resistance, Urinary tract infection, Multidrug-resistant (MDR), Extensively drug-resistant (XDR), Pandrug-resistant (PDR)