Thesis (M.Sc.) - Cairo University - Faculty of veterinary Medicine - Department of Zoonoses

Food-borne diseases are of major concern worldwide, Staphylococcus aureus among the predominant bacteria involved in these diseases; it is a leading cause of gastroenteritis resulting from the consumption of contaminated food. Therefore a total of 483 food samples (246 chicken & 237 beef meat) and 120 equipment swab samples that retailed at 112 food outlets in Egypt were investigated bacteriologically for contamination with S. aureus. Additionally, 121 hand swabs of food handlers were gathered from the same outlets. S. aureus was isolated from 57 (11.8%), 4 (3.3%) and 13 (10.7%) food, equipment and hand swabs samples, respectively. The higher rate of isolation of S. aureus was observed in chicken meat (13.8 %) than those recorded in the examined beef meat (9.7%). Using PCR, 18 (29.5%) of 61 isolates were enterotoxigenic, in addition only 2 (15.4%) of 13 isolates belonged to the human were enterotoxigenic. Most of the enterotoxigenic isolates belonged to raw chicken samples (37.5%) followed by the cooked beef meat (30.0%). At least one of the following enterotoxins coding genes was detected in 20 enterotoxigenic strains SEC, SED, SEG, SEH; some isolates were found have more than one SEs genes and none of those carries SEA, SEB or SEE.Among the SED-producing isolates (chicken, beef, knife and human swab samples) sequencing and phylogenetic analysis evidenced that both cooked chicken and beef meats as well as knife sequence were grouped in the same cluster with the human sequence rather than raw chicken which placed in another one. Such phylogenetic analysis may point out to the incrimination of food handlers in the contamination of not only cooked food but also articles such as knife mentioning that this isolate obtained from a knife used only for cutting cooked food

Issued also as CD