Antimicrobial Resistance Pattern of Escherichia coli Isolated from Chickens with Colibacillosis in Yazd, Iran

Background: The antibiotic resistance is considered as one of the biggest public health concerns in most countries. The aim of this study was to determine antibiotic resistance pattern of Escherichia coli isolated from chickens with colibacillosis in Yazd, Iran. Methods: A total of 200 carcasses of Ross chickens with colibacillosis were collected from farms located around Yazd, central Iran. After autopsy, specimens were collected from air bags of carcasses using sterile swaps and transferred immediately to the laboratory. After microbiological culture, the isolates were confirmed by the conventional Polymerase Chain Reaction (PCR) assay. Antimicrobial susceptibility of E. coli isolates were determined by disk diffusion method. Results: Out of 200 specimens, 100 (50%) E. coli isolates were identified and confirmed by PCR method. The results of antimicrobial susceptibility tests showed the highest resistance against nalidixic acid (100%), enrofloxacin (87%), ciprofloxacin (86%), and erythromycin (82%), respectively. Also, the highest susceptibility was seen for colistin (100%), meropenem (94%), and gentamicin (93%), respectively. Conclusion: In this study, multidrug resistance was observed in avian pathogenic E. coli isolates that represents the heavy usage of these drugs in poultry flocks in Yazd, central Iran. Improper or overuse of antibiotics usage for treatment of the poultry diseases could play an important role in spreading of the antimicrobial resistance genes among pathogenic bacteria from human and animals especially through food chain.