الفهرس 
English SummaryOnly 14 pages are availabe for public view
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Abstract
Ongoing screening of food and related processing, storage, and equipment for foodborne pathogens is required to determine the overall hygiene of food premises and the effectiveness of the cleaning and disinfection program implemented. It is also necessary to have a better understanding of the virulence factors of foodborne pathogens, which is a growing topic, in order to identify the most effective preventive and control measures within the security of food supplies. The prevalence of Escherichia coli, Staphylococcus aureus and Salmonella on swabbed surfaces and equipment from butchers and supermarkets were targeted in the current study. Biochemical identification of isolates swabbed from one hundred food contact surfaces and equipment using the VITEK2 compact system yielded presumptive incidences of Escherichia coli, and Salmonella of 31, and 11%, respectively. Serotyping confirmed Escherichia coli and Salmonella incidences of 20% and 2%, respectively. While Staphylococcus aureus presumptive and VITEK2 compact system confirmed incidences were 60% and 25%. Butchers had a higher prevalence of E. coli and S. aureus than supermarkets (P <0.05). Additionally, although it was not statistically significant, butchers had a higher prevalence of Salmonella than supermarkets (P >0.05).
Serotyping of the twenty Escherichia coli isolates revealed that half of the twelve butchers isolates were enterohaemorrhagic Escherichia coli (EHEC), three were enteropathogenic (EPEC), two were enterotoxigenic (ETEC), and only one was enteroinvasive Escherichia coli (EIEC). Enterohaemorrhagic Escherichia coli (EHEC) was also prevalent in supermarkets, While enteropathogenic (EPEC) and enterotoxigenic (ETEC) both contributed three isolates, and enteroinvasive Escherichia coli (EIEC) was not detected. It is worth noting that some butchers and supermarkets recovered multiple E. coli serogroups. For example, from swabbed cutting boards, fillers, and/or mincers, eleven isolates were recovered from five butcher shops, yielding either three serogroups (1 shop) or two (4 shops), data not shown. All Salmonella isolates were Salmonella enterica serovars Typhimurium and were both obtained from distinct butcheries.
The csgA, Crl, and stx1 genes were identified in three butcher’s EHEC isolates and one supermarket EHEC isolate. Two isolates, one from EPEC and one from ETEC, expressed biofilm-forming genes, CsgA and Crl, whereas two isolates from ETEC and EIEC did not express biofilm or other virulence genes. Genetic expression of the invA and sdiA
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genes was observed in both S. Typhimurium isolates, and one of them also expressed the sipA gene icaA. All S. aureus isolates contained the 16s rRNA gene. The mecA gene was found in two of the five S. aureus isolates. All five Staphylococcus aureus isolates tested positive for icaD, and three of them shared icaA.
In conclusion, in 20%, 2%, and 25% of swabbed samples, respectively, E. coli, Salmonella, and Staphylococcus aureus were confirmed. Butchers had higher rates of targeted pathogen detection than supermarkets (24%, 4 and 30% vs. 16%, 0 and 20%, respectively) (P > 0.05). The eight serotypes of Escherichia coli isolates were classified into four pathotypes (55% enterohaemorrhagic (EHEC), 20% enteropathogenic (EPEC), 20% enterotoxigenic (ETEC), and 5% enteroinvasive). (EIEC). Six of the eight E. coli isolates co-expressed Crl in all CsgA biofilm genes, with four of them, EHEC, also expressing Stx1. Both S. Typhimurium strains expressed the invA and sdiA genes and one of them also expressed the sipA gene. While three Staphylococcus aureus isolates simultaneously shared the icaA and two of the three shared the mecA resistance gene, all five isolates shared the icaD biofilm-forming gene and the pyrogenic exotoxin (PT) genes. The genetic identification of virulence factors like Stx1, invA, PT, and mecA resistance genes from pathogens isolated from surfaces that come into contact with meat, especially in butcheries, combined with a high incidence of biofilm-producing genes, is a serious concern that needs to be immediately controlled; otherwise, it could potentially contaminate fresh meat products and carcasses, and eventually people via the food chain.