Molecular Characterization of Antimicrobial-resistant Escherichia coli Isolated from Broiler Chickens

Document Type : Original Article


1 Bacteriology, Mycology and Immunology Department, Faculty of Veterinary Medicine, Beni-Suef University, Beni-Suef 62511, Egypt

2 El-Minia Directorate of Veterinary Medicine, Egypt


Avian colibacillosis is one of the most important diseases of chickens resulting in significant economic losses as well as high morbidity and mortality. In the current study, the prevalence of avian colibacillosis was studied in different farms of broiler chickens in Beni-Suef, EL-Minia, ElFayoum, Assiut and Sohag Governorates. A total of 300 pooling samples were collected aseptically from heart blood as well as the affected organs including air sacs, pericardial sac, and liver of slaughtered diseased and freshly dead broiler chickens. Bacteriological examination of the collected samples showed that a total number of 80 E. coli isolates were recovered with an overall prevalence of 26.7. The highest prevalence was recorded in El-Fayoum (33.3%) followed by El-Minia (25%), Beni-Suef and Assiut (22.5% for each) while the lowest prevalence was in Sohag (17.5%). The invitro antimicrobial susceptibility testing revealed that E. coli isolates showed high sensitivity to colistin sulphate only (70%). Meanwhile, high resistances were recorded against other antimicrobials including amoxicillin (97.5%), cefotaxime sodium and florfenicol (95% for each), apramycin, ciprofloxacin and gentamicin (92.5% for each), streptomycin (90%), enrofloxacin (87.5%), trimethoprim-sulphamethoxazol and doxycycline HCl (77.5% for each). All E. coli isolates were MDR (100%). PCR was applied on 10 MDR E. coli isolates to detect the 3 resistance-associated genes (qnrA, tetA and aac(6′)- Ib-cr and 5 virulence-associated genes (iutA, hly, sta, lt and astA). The results showed that all the tested isolates (100%) harbored qnrA, tetA, iutA and astA genes meanwhile aac(6′)-Ib-cr, hly, sta and lt genes were not detected in any isolate.


Main Subjects