الفهرس 
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Abstract
In the present study, fifty minced meat samples from butcher’s shops in three Egyptian Governorates were randomly collected in summer and winter seasons and analyzed for isolation of Staphylococcus aureus, Salmonella species, Escherichia coli and Listeria monocytogenes. The total bacterial counts were 9 x 105 , 1 x 106 CFU /g and the coliform counts were 7 x 102, 8 x 102 CFU /g, in winter and summer seasons respectively. S. aureus, E. coli, Salmonella spp., Listeria spp. and L. monocytogenes were isolated from 12(24%), 44 (88%), 3(6%), 9(18%) and0.0 (0%) samples respectively. Further, 37(84.1%) of 44 E. coli isolates were belonged to the following serotypes (O1, O26, O125, O126, O146, O166, O18, O114, O151, O157, O158, O27, O78, O148, O159, O168 and O8), while 7 isolates (15.9%) were untypable with the available antisera.
Detection of staphylococcal enterotoxins (A, B, C and D) in minced meat samples, the results showed that all S. aureus isolates gave negative for staphylococcal enterotoxins (A, B, C and D).The thirty seven E. coli isolates screened for the detection of verocytotoxin producing E .coli (VTEC). Results showed that all minced meat samples gave negative for VT (vt1, vt2 and eae) detection except one minced meat sample (E. coli O114 isolate) gave positive results for VT with percentage (2.7%).
Determination of the antibacterial activity of essential oils (rosemary, peppermint, spearmint, garlic, cumin and cinnamon) on isolated bacteria from minced meat samples compared with sodium nitrite in vitro by agar well diffusion assay through inhibition zone (mm) and determination of (MIC and MBC).Results showed that cinnamon has bactericidal activity against all the tested bacteria. Determination of the antitoxic effect of (cinnamon, cumin and garlic) oils and sodium nitrite on verocytotoxin producing E. coli 0114 was determined, results showed that (cumin and garlic) oils and sodium nitrite were nondestructive to VTEC (vt1, vt2 and eae) genes , however VTEC completely destructed by treatment with cinnamon oil. This is due to an active component of the cinnamon oil, which purified by (GC- MS) and identified as eugenol (1.72%), has suppressive effect on VT production. Eugenol is useful for reducing the virulence of E. coli, which produced VT.