الفهرس 
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Abstract
A total of 180 fresh shell fish samples (50 Shrimp , 40 Squid , 50 Crab and 40 Octopus Vulgaris) were collected from different retail stores and hypermarkets in Alexandria governorate during summer of 2017 and 2018. All the samples were examined bacteriologically for the detection of Vibrio species. Identification V.parahemolyticus isolates was confirmed by Multiplex PCR for detection of pathogenic genes (TLH, RecA, TRH and TRH genes) after that the samples that were infected with V. parahemolyticus were subjected to test the ability of V. parahemolyticus for decarboxylation and production of biogenic amine (Histamine and Putrescine) in vitro by Niven’s test.
The study showed that the incidence ofV.parahemolyticus,V.cholera,V.alginolyticusand V.vulnifius were 11(22%) , 0(0%) , 4(8%) and 5(10%) isolates in Shrimp respectively.
The incidence of V.parahemolyticus ,V.cholera ,V.alginolyticus and V.vulnifius were 2(5%) , 5(12.5%), 8(20%) and 0(0%) isolates in Squid respectively, the incidence of V.parahemolyticus ,V.cholera,V.alginolyticus and V.vulnifius were 6(12%) , 3(6%) ,10(20%) and 0(0%) isolates in Crab respectively , the incidence of V.parahemolyticus ,V.cholera,V.alginolyticus and V.vulnifius were 0(0%) ,9(22.5%) ,2(5%) and 4(10%) isolates in Octopus Vulgaris respectively , the incidence of Vibrio species in Shrimp were 19(38%) isolates , in Squid were 15(37.5%) isolates , in Crab were 19(38%) isolate and in Octopus Vulgaris were 15(37.5%) isolate and the incidence of V.parahemolyticus strains were 19 (10.5%)isolate ,V.cholera were 17(9.4%) isolate ,V.alginolyticus were 24(13.3% ) isolate andV.vulnifius were 9(5%) and overall incidence were 69 (38.3%) in all shellfish samples.
The most contaminated samples with Vibrio species were Shrimp and Crab (19 Vibrio isolates) for each one of them then Squid and Octopus Vulgaris (15 Vibrio isolates) for each one of them.
Genetic identification of 19 V.parahemolyticus strains revealed presence of (19 TLH with amplicon 449 bp ,18 RecA with amplicon 793bp as one sample did not contain RecA gene) and all the isolates were negative for (TDH,TRH) by Multiplex PCR.
All the 19 samples that were infected with V.parahemolyticus strains were able to decarboxylase histidine to histamine and ornithine to putrescine in vitro. This gives us an indicator for the high decarboxylating activity of V.parahemolyticus and it’s ability to cause Biogenic amine food poisoning through accumulation of Histamine and Putrescine.
The results from the current study indicated the genetic diversity among V.parahemolyticus isolates as the specific genes for V.parahemolyticus were detected in three different species (Shrimp , Squid and Crab ). Niven’s test indicated this genetic diversity by testing the decarboxylating ability of V.parahemolyticus isolates where the isolates proved to have the genes of decarboxylation and produce Histamine and Putrescine .
This study described why V.parahemolyticus isolates can cause food poisoning due to it ’s presence in the food samples.This enteropathogen proved to cause biogenic amine food poisoning and the interpretation of that is the highly genetic diversification of V.parahemolyticus.
Public health hazard of isolated Vibrio Spp. (V.parahemolyticus,V.cholera , V.alginolyticus and V.vulnifius) , from sample shellfish were discussed.