Seyyed Sattar Tohidifar - Department of Avian Medicine, School of Veterinary Medicine, Shshrekord University
Zahra Hemmati - Department of pathobiology, School of Veterinary Medicine, Shahrekord University

Background and Aim : Escherichia coli is a gram negative, non-spore forming bacillus and it is a common inhabitant in the intestinal tract of poultry. During the last decades, excessive reliance on antibiotics in human and animal medicine has contributed to creating favourable conditions for the selection, persistence and spread of antibiotic resistant bacteria. To prevent of Escherichia coli infection, it's necessary to determine resistance of bacteria to antibiotics. Disk diffusion method is one of the most common antibiogram methods. In this study we measured antibiotical resistance of E. coli isolates from broiler chickens in Chaharmahal and Bakhtiari province during October ۲۰۱۸ to October ۲۰۲۰.Methods : Sampling was made out of pericardial sac and liver of ۴۵۸ dead birds referred to clinical department of Shahrekord University, which were affected to colibacillosis and then cultured according to standard operation method. Antibiotical resistance to a panel of antibiotics was determined through disk diffusion method for ۱۰۰ E. coli isolates. Due to bacterial resistance to antibiotics, diameter of lack growth halo varies. Results of antibiogram is reported to sensitive, intermediate and resistant.Results : The percentages of isolates that were resistant to ۱۰ antibacterial agents during ۲۰۱۸-۲۰۲۰ were as follows: Erythromycin: ۹۲.۷%, oxcytetracycline: ۸۹.۴%, Danofloxacin:۷۹.۲%, Difloxacin: ۸۲.۸%, Enrofloxacine: ۷۵.۶%, Doxcycycline: ۷۷.۵%, Ciprofeloxacin: ۶۸%, Lincospectin: ۵۳.۶%, Sultrim: ۷۲% and Florfenicole: ۵۶.۲%. Conclusion : The association between the occurrence of resistance and the consumption of the antimicrobial agents is discussed. The present study highlights the prevalence of multiple drug resistant E. coli among healthy broiler chickens in mentioned province. The comparison of resistance patterns reported here with pervious investigations indicated that the resistance to some antibacterial agent among E. coli isolates from avian colibacillosis is on the rise and this may be of concern for poultry specialists.

Antibiotic Resistance, antibiogram, Escherichia coli, Chaharmahal and Bakhtiari province, Iran