en باکتری شناسی پزشکی Medical Bacteriology مقاله پژوهشی Original Research Article <p style="text-align: justify;"><span style="font-size:16px;"><span style="font-family:Times New Roman;"><b><span style="background:#1f497d"><span style="color:white"><span style="letter-spacing:-.1pt">Background and Aim:</span></span></span></b> <span lang="EN-ID">Avian pathogenic <em>Escherichia coli </em>(APEC) is a major cause of colibacillosis in poultry, contributing to systemic disease and economic loss. This study investigated virulence genes profile, biofilm formation, and antimicrobial and disinfectant resistance in <em>Escherichia (E.) coli</em> isolates from broiler chickens in Qazvin, Iran.</span><br> <b><span style="background:#1f497d"><span style="color:white"><span style="letter-spacing:-.1pt">Materials and Methods:</span></span></span></b> <span lang="EN-ID">Liver samples were collected from 50 broiler chickens diagnosed with colibacillosis. <em>Escherichia coli</em> isolates were confirmed biochemically. Antibiotic susceptibility was evaluated using disk diffusion method, and virulence genes were detected via PCR. Biofilm formation was assessed using crystal violet staining. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values for formaldehyde, glutaraldehyde, and hydrogen peroxide were determined using broth microdilution.</span><span style="color:black"> </span><br> <b><span style="background:#1f497d"><span style="color:white"><span style="letter-spacing:-.1pt">Results:</span></span></span></b> <span lang="EN-ID">Among 50 isolates, 82% exhibited multidrug resistance (MDR) and 30% were extended-spectrum beta-lactamase (ESBL) producers. The most frequent and the least common genes were <em>iss </em>(66%), and <em>papC</em> (4%), respectively. All isolates formed biofilms, with 72% classified as strong producers. Formaldehyde and hydrogen peroxide exhibited the lowest MIC and MBC values (&le; 0.009%), while glutaraldehyde required higher concentrations for inhibitory and bactericidal activity (0.078%).</span><br> <b><span style="background:#1f497d"><span style="color:white"><span style="letter-spacing:-.1pt">Conclusion:</span></span></span></b>&nbsp;High rates of MDR and biofilm formation among APEC isolates highlight the need for effective antimicrobial stewardship and disinfection strategies in poultry production systems.</span></span></p> Antimicrobial Resistance, Biofilm, Broilers, Escherichia coli, Pathogenic Genes 171 181 http://ijmm.ir/browse.php?a_code=A-10-2800-1&slc_lang=en&sid=1 Nazanin Alijani Nazaniiinnazi904@gmail.com 100319475328460032384 0009-0009-7150-3186 No Medical Microbiology Research Center, Qazvin University of Medical Sciences, Qazvin, Iran Mohadeseh Khakpour mohadkhakpour77@gmail.com 100319475328460032385 100319475328460032385 No Medical Microbiology Research Center, Qazvin University of Medical Sciences, Qazvin, Iran Samira Sabzi samira6913@yahoo.com 100319475328460032386 100319475328460032386 No Medical Microbiology Research Center, Qazvin University of Medical Sciences, Qazvin, Iran Fatemeh Fardsanei atefeh_fardsanei@yahoo.com 100319475328460032387 100319475328460032387 No Medical Microbiology Research Center, Qazvin University of Medical Sciences, Qazvin, Iran Saeed Sayfzadeh saeedsayfzadeh@yahoo.com 100319475328460032388 100319475328460032388 No Department of Agronomy, Takestan Branch, Islamic Azad University, Takestan, Iran Abolfazl Alizadeh Shamlu abolfazlalizade862@gmail.com 100319475328460032389 0009-0005-8461-138X No Medical Microbiology Research Center, Qazvin University of Medical Sciences, Qazvin, Iran Farhad Nikkhahi farhadnikkhahi@gmail.com 100319475328460032390 100319475328460032390 Yes Medical Microbiology Research Center, Qazvin University of Medical Sciences, Qazvin, Iran