الفهرس 
IntroductionOnly 14 pages are availabe for public view
 |  | from | 146 |  |  |
| | | from | 146 | | |
Abstract
This study was done on 500 diseased broilers chickens (3-4 weeks of age)
from March 2016 to December 2017 . the collected samples suffered from pericarditis, perihepatitis, and airsacculitis (liver ,heart and cloacal swabs from each sample) were collected from different area in Sharkia province. Bacteriological examination revealed that the prevalence of E.coli was (12.8%) from the collected samples. Out of 500 samples of examined fresh heart blood 36 were E.coli positive with an incidence 7.2%.Regarding examined liver samples 7.6 % were positive, while 40% from cloacal swabs. All samples were submitted for isolation and biochemical identification for E.coli.(Congo red binding assay) indicates that (40%) of the isolated E. coli isolates were positive. Serological identification of E.coli isolates revealed that E.coli isolates were belong to 10 different serotypes which were identified as follows O78 with 21.9%, O2 with 9.6 %, O91 with 7 %, O125 with 6.1 % , O1, O44, O128 and O111 which had the same isolation rate with 5.3 % each , O26 with 3.5 % and finally the lowest prevalent serotypes O121 with 2.6 %. Disc diffusion test of E. coli isolates showed the highest resistance against Lincomycin (100%), tetracycline( 96.8 %), streptomycin (93.7%).
In the PCR screening all isolates were positive for iss gene and ompA gene while papC gene (91.66%),tsh gene (83.3%),iroN gene 75 %,while eaeA gene 16.7 % and PCR failed to detect stx1and stx2 in the tested isolates.