الفهرس 
REVIEW OF LITERATUREOnly 14 pages are availabe for public view
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Abstract
A total of 250 random meat product samples (50 each of minced meat, beef burger, beef sausage, beef kofta and beef luncheon) were collected from different super markets at different localities for detection of Escherichia coli using conventional method and Polymerase chain reaction. Conventional method indicated that E. coli could be isolated from of minced meat, beef burger, beef sausage, beef kofta and beef luncheon in a percentage of 46%, 28%, 32% , 36% and 16% respectively. While Polymerase chain reaction detected E. coli in of minced meat, beef burger, beef sausage, beef kofta and beef luncheon in a percentage of 38%, 22%, 30%, 32% and 12% respectively.
The present study was planned to investigate the presence of Shiga toxin-producing E. coli (STEC) in meat products sample as examined by Vero Cytotoxicity Assay (VCA) and confirmed by Serotyping and Multiplex Polymerase Chain Reaction.
It is obvious that in the Vero cytotoxicity assay the percentage of shiga-toxin producing E.coli were 60.8%, 50%, 43.7% , 50% and 12.5% of minced meat, beef burger, beef sausage, beef kofta and beef luncheon, respectively in relation to total number of isolated positive E. coli samples.while by Mutiplex PCR method the percentage of shiga-toxin producing E.coli were 47.8%, 42.8%, 31.3%, 44.4% and 12.5% of minced meat, beef burger, beef sausage, beef kofta and beef luncheon, respectively
The serological identification of shiga-toxin producing E.coli isolated from the examined minced meat samples were O111, O26, O103 , O119 ,O128 ,O86, O146 and O121. While for beef burger samples, the isolated serovars were O111, O26 , O103 ,O86, O146 and O45. But the isolated serovars from beef sausage were O111, O103 , O119 O86 and O45.The isolated serovars from beef kofta were O111, O26 , O91 ,O128 ,O86, and O146. Finally the only one serovars isolated from beef luncheon was O119.
The use of Multiplex PCR with specific primers for Stx1, Stx2 ,eae and ehly genes revealed the presence or absence of these genes in the tested isolates. The obtained results showed that the isolates E. coli O111, O26, O103, O91, O86 and O119 had Stx1 and Stx2 genes while, E.coli O128 and O121 had only Stx1. E.coli O146 had only Stx2.Concerning the eae gene responsible for the attaching and effacing lesions, E. coli O111 and O26 isolates possessed this gene .
The second part of this study was planned to explore the effect of Nisin alone or combined with chemical preservatives on the growth of E.coli O111:H4. The obtained results allow to conclude that the best formula to destroy all organisms of E.coli including O111: H4 in minced beef is the application of nisin by concentration of 10 ppm and 30 ppm coupled with sodium lactate(0.2%) for 24 and 48 hours to obtain a maximum margin of human safety against such serious pathogen.