Antimicrobial resistance and molecular characterization of pathogenic E. coli isolated from chickens

Document Type : Original Article


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

2 Animal Health Research Institute, Dokki, Giza, Egypt.

3 Animal Health Research Institute, Beni Suef, Egypt.

4 Department of Microbiology, Faculty of Veterinary Medicine, NewValley University, Egypt.


Forty eight clinically diseased broiler chickens from different (n=18) farms from Beni Suef and El-Fayoum Governorates were subjected to euthanasia and post mortem examination. Lesions include airsaculitis, pericarditis and perihepatitis. Bacteriological examination showed that 22.9% of isolates were E. coli positive. Serogrouping of isolates revealed O125, O112, O91, O157, O115 and O25 % of each serogroups with an incidence rate of 18.2%, 9.1%, 9.1%, 9.1%, 9.1%, and 9.1%, respectively and four strains were untyped. Antimicrobial sensitivity tests against 17 antimicrobials showed that  the most common resistance patterns were against penicillin, lincomycin, oxytetracycline, clindamycin, amoxycillin and erythromycin followed by nalidix acid and trimethoprim. On the other hand, the most potent antimicrobials were colistin sulphate, gentamycin, doxycycline and ceftriaxone followed by enrofloxacin, ciprofloxacin, norfloxacin, chloramphenicol and lastly ampicillin. PCR showed that all isolates had B-lactam resistant gene (blaTEM) and tetracycline resistance gene A (tetA) but only 18 % have quinolones resistance gene A (qnrA).


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