الفهرس 
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Abstract
Summary: As milk and meat products are subjected to contamination with a lot of microorganisms from different sources either during production, manufacturing and/or handling especially with S. aureus and C. perfringens which find in milk and meat products a good media for growth, multiplication and production of toxins so that it becomes a source of food poisoning to man.
The purpose of this study is evaluation of immunological and bacteriological patterns of some food poisoning micro-organisms (Staphylococcus aureus and Clostridium perfringens).
Two hundred samples of different milk and meat products were included in this study, as:
• One hundred sample of milk products including hard cheese and kareish (50 of each).
• One hundred sample of meat products including luncheon and sausage (50 of each).
Out of 200 examined samples of milk and meat products, S.aureus was detected in 40% and 30% of milk and meat products samples, respectively. While C.perfringens was detected in 18% and 23% of milk and meat products samples, respectively.
In case of milk products samples, S. aureus was isolated from hard cheese and kareish samples with percentage of 52% and 28%, respectively, while C.perfringens was isolated from hard cheese and kareish cheese samples with percentage of 16% and 20%, respectively.
In case of meat products samples, S. aureus could be isolated from luncheon and sausage samples with percentage of 24% and 36% respectively, while C.perfringens was isolated from luncheon and sausage samples with percentage of 22% and 24%, respectively.
All S. aureus isolates were Gram positive cocci arranged in clusters, they were catalase and coagulase producer, growth occurred on Baird Parker medium, nutrient agar, blood agar and mannitol salt agar. All isolates fermented glucose anerobically.
The recorded C. perfringens isolates were subjected to the following biochemical tests: catalase, sugar fermentation, gelatin liquefaction, litmus milk and indole tests. The obtained results showed that C. perfringens is catalase negative, glucose, maltose, lactose sucrose and mannose positive but mannitol negative, gelatin liquefier, litmus milk positive and indole negative.
Moreover, Nagler`s test was applied on the recovered C. perfringens isolates to detect the action of alpha toxin (lecithinase) on lecithin of egg yolk onto enriched egg yolk agar medium. The results showed pearly opalescence zones surround the colonies while this reaction was inhibited by C. perfringens alpha toxin antiserum.
Reversed passive latex agglutination technique (RPLA) was applied on S. aureus isolates to detect the presence of staphylococcal enterotoxins A, B, C and D.
In case of S. aureus isolates obtained from milk products, it was found that only 13 (32.5%) from 40 S. aureus isolates were enterotoxigenic as, 9 stated to produce enterotoxin (A) (22.5%) and 3 produced enterotoxin (B) (7.5%) and production of enterotoxin (C) observed in 1 isolate (2.5%), while all the isolates didn’t produce enterotoxin (D).
In case of S. aureus isolates obtained from meat products, it was found that only 17 (56.67%) 30 S. aureus isolates were enterotoxigenic as, 8 stated to enterotoxin (D) (26.67%) which was the highest, then 6 produced enterotoxin (A) (20%) and production of enterotoxin (B) observed in 3 (10%) isolates, while all the isolates didn’t produce enterotoxin (C).
C. perfringens isolates recovered from milk and meat products were biologically examined for their toxicity by I/V inoculation in Swiss mice (3 animals / isolate).
The toxicity of C. perfringens isolated from hard cheese and kareish cheese were 75% (6) and 70% (7), respectively while from luncheon and sausage were 63.64% (7) and 66.67% (8), respectively.
All twenty eight toxigenic C. perfringens isolates from milk and meat products were type A by dermonecrotic reactions, toxin antitoxin neutralization tests (on the skin of albino guinea pigs).
Mice injected with MLD (80/ml) of C. perfringens alpha toxin exhibited significant decrease in phagocytic percentage and index at 3 and 6 days post injection compared with control. Also there was significant decrease in serum lysozyme activity and nitric oxide.
In the present study, Polymerase chain reaction (PCR) has been proved to be a reliable, sensitive and specific protocol for detection of the genes encoding staphylococcal enterotoxins (A to E), also C. perfringens alpha exotoxin as well as enterotoxin as a recent confirmatory technique for conventional methods.
Total number of 10 isolates (5 isolates from milk products and 5 isolates from meat products) tested by using RPLA and the results of