الفهرس 
SeafoodOnly 14 pages are availabe for public view
 |  | from | 76 |  |  |
| | | from | 76 | | |
Abstract
Food borne diseases are the most wide spread health problem in the world and they have implication both on health and development.
Salmonella Spp. are significant microbial hazards in seafood and rapid detection of Salmonella is an important criterion in quality control of seafood.
The present study aimed to:
Determine the percentage of Salmonella in seafood from some markets in Alexandria and to study the validity of CHROMagar Salmonella Plus medium versus conventional method; Xylose Lysine Desoxycholate (XLD) and Salmonella-Shigella (SS) agar for the isolation and identification of Salmonella in some seafoods.
The study was carried out on 225 seafood samples collected from 11 different localities in Alexandria. Each sample was collected in a sterile container, labeled and transferred to the laboratory for complete examination.
Detection of Salmonella was done as follows:
1. 25 g of seafood samples homogenized with 225 ml of buffered peptone broth in a stomacher for 30 second.
2. The samples were pre-enriched in buffered peptone broth, incubated for 18- 20h at 37ºC.
3. After incubation, 0.1 mL was transferred to 10 mL of Rappaport-Vassiliadis broth (RV) and 1mL to 10 mL of tetrathionate broth (TT), both incubated at 42ºC for 24h.
4. A loopfull from each broth was streaked onto SS agar, XLD agar and CHROMagar Salmonella Plus medium and incubated for 24h at 37ºC.
5. All colonies suspected as Salmonella were biochemically identified according to standard microbiological methods and submitted to serological tests using polyvalent somatic antisera.
The results of this study can be summarized as follows:
1. Out of the 225 seafood samples, Salmonella was detected in 9.8% of the samples.
2. Out of 75 of each of shrimp, gandofli and River mussel (om- khloul) samples, Salmonella was detected in 17.3%, 8% and 4% of the samples respectively.
3. The highest percentage of Salmonella isolation was from Karmouz 15%, followed by Khourshid 12.5%, then El-Manshia and Mahatet-Misr each 12%.
4. CHROMagar Salmonella Plus medium detected 81.82% of Salmonella isolates after enrichment in TT and 95.45% after enrichment in RV.
5. XLD agar detected 50% of Salmonella isolates after enrichment in TT and 72.73% after enrichment in RV.
6. SS agar detected 63.64% of Salmonella isolates after enrichment in TT and 81.82% after enrichment in RV.
7. The specificity of CHROMagar Salmonella Plus medium after enrichment in TT was 99.5% and after enrichment in RV increased to 100%.
8. The specificity of XLD after enrichment in TT was 84.7% and increased to 100% after enrichment in RV.
9. The specificity of SS agar after enrichment in TT was 40% and increased to 93.6% after enrichment in RV.
10. The accuracy of CHROMagar Salmonella Plus medium after enrichment in TT was 97.8% and after enrichment in RV increased to 99.5%.
11. The accuracy of XLD after enrichment inTT was 81.3% and increased to 97.3% after enrichment in RV.
12. The accuracy of SS agar after enrichment in TT was 42.2% and increased to 92.4% after enrichment in RV.
It can be concluded from this study that:
1. Seafood is a potential vehicle for transmitting food borne disease since Salmonella was detected in 9.8% of the seafood samples which is the leading cause of both typhoid and food poisoning diseases. Its presence reflects the prevalence of the organism in seafood, or the bad hygienic quality of seafood.
2. RV was found to be superior to TT in the isolation of Salmonella from seafood samples.
3. SS agar medium with TT is the worst combination in the detection of Salmonella from seafood.
4. CHROMagar Salmonella Plus medium was found to be more valuable than XLD and SS in the detection of Salmonella from seafood samples. It provides a time saving method for the detection and presumptive identification of Salmonellae from seafood specimens. Interpretation of colors was easy, and all colonies of Salmonellae tested displayed the same color and morphology.