الفهرس 
IntroductionOnly 14 pages are availabe for public view
 |  | from | 144 |  |  |
| | | from | 144 | | |
Abstract
A total one hundred random samples of fresh Tilapia nilotica samples were purchased from different fish market in Shoubra and Abbasia, Cairo governorate and Benha, Kaliobeya governorate and also from farm fish in Al-Boheira governorate. Collected samples were bacteriologically examined for detection of L. monocytogenes. The obtained results revealed that seven of L. monocytogenes isolated from fresh Tilapia nilotica fish samples in Egyptian fish market identified by biochemical test. The seven isolates which recorded by biochemical test was exposed to PCR technique and only four isolates were confirmed to be L. monocytogenes. The highest prevalence of Listeria monocytogenes (3%) was observed in fresh Tilapia nilotica from marketed fish while lower prevalence (1%) was seen in fresh Tilapia nilotica from farm fish. Concerning the other listeria species isolated from the examined samples of fresh Tilapia nilotica were 27 isolates, eight isolates (8%) were L. ivanovii, five isolates (5%) were L. innocua, five isolates (5%) were L. seeligeri, six (6%) isolates were L. welshimeri, and three (3%) isolates were L. grayi and L. murryi was not isolated from any examined fish.Concerning experimental part 9 samples of fresh Tilapia nilotica fish were exposed to heat treatment by 3 methods (frying, grilling and cooking in oven) were done. The results revealed that the best and faster method for treatment by heating is frying at 190c/10min which completely destroyed L. monocytogenes by 100%.
The public health significance of the isolated microorganisms and the probable sources of Nile fish contamination as well as some recommendations to prevent them to gain access to such food items were discussed.