الفهرس 
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Abstract
A total of one hundred samples of meat and poultry products including Beef salami, Beef escalope panee, chicken shesh tawook and chicken Pattie were collected randomly from the supermarkets in kalyobia governorates and transferred in an ice box as soon as possible to the laboratory to be examined. For the presence of listeria monocytogenes and other Listeria species. Isolation of these pathogen was conducted by the USDA – FSIS technique, by using two enrichment media (UVMI and UVMII) followed by isolation in PALCAM agar. The suspected positive colonies were then confirmed by several biochemical tests. L.monocytogenes was isolated from 4% of meat product samples only from beef escalope panne and from 8% of poultry product samples only from chicken Pattie. L.monocytogenes failed to be detected in beef salami samples and chicken shesh tawook samples. The present study revealed that L.Ivanovii and L.welshmeri were isolated in a percentage of 4% for each while L.murrayi and L.seeligeri failed to be detected in the examined beef salami. L.Ivanovii and L.murrayi failed to be detected in the examined beef escalope panne while L.seeligeri and L.welshmeri were isolated in a percentge of 8% and 4% respectively. In this study, examination of chicken shesh tawook revealed that L.Ivanovii, L.murrayi and L.welshmeri were isolated in a percentage of 8%, 4% and 8% respectively while L.seeligeri failed to be detected. L.Ivanovii, L.murrayi and L.seeligeri were isolated in a percentage of 12%, 4% and 4% respectively from the examined chicken Pattie while L.weleshmeri failed to be detected. from these results it is concluded that chicken Pattie is highly contaminated with all listeria species followed by chicken shesh tawook, while meat products were less contaminated. Beef escalope panee was used as a model, Nisin (2.5%) was added in three concentration 10, 30 and 50ppm and examined in hours 0, 12th and 24th to examine the L.monocytogenes count. So, addition of bacteriocin as Nisin (2.5%) in different concentration (10, 30and 50p.p.m) was used in controlling listerial growth in these products. Nisin (2.5%) in 10ppm concentration has antilisterial effect as it decreased the number of inoculated L.monocytogenes from 5x106 to 2.92x105 then to 8.30x103 by the time periods. While at 30p.p.m and 50p.p.m concentration it has amore powerful and fast antilisterial effect as 30p.p.m concentration of Nisin (2.5%) decreased the number of L.monocytogenes from 5x106 to 7.81x104 then to 0 by time periods while 50p.p.m concentration of Nisin (2.5%) decreased the number of L.monocytogenes from 5x106 to 1.64x104 then to 0 by time periods.