Thesis (M.Sc.) - Cairo University - Faculty of Veterinary Medicine - Department of Food Hygiene and Control

Fifty raw milk samples and sixty pasteurized milk samples (30 unflavoured and 30 flavoured) were obtained from shops and supermarkets in Cairo and Giza Governorates, Egypt. Staphylococci were present in all of the examined samples, with mean count of 7.0x106, 5.5x103 and 3.5x105 CFU/ml of raw, unflavoured and flavoured pasteurized milk, respectively. Coagulase Positive Staphylococci was present with mean count of 2.7x106, 1.4 x103 and 6.4 x102 CFU/ml of raw, unflavoured and flavoured pasteurized milk, respectively. The Coagulase Positive Staphylococci (CPS) and TNase isolated from the examined raw milk samples were in a percentage of 38.06 and 30.77, respectively. While CPS isolated from the examined unflavoured and flavoured pasteurized milk were in a percentage of 30.21 and 19.11 respectively. CPS beta hemolytic isolates of raw milk samples were found in a percentage of 74.47, while in unflavoured and flavoured pasteurized milk were found in a percentage of 44.83 and 16.67 respectively. The CPS isolates of examined milk samples gave 100.00% positive for staphytect plus test. Coagulase Positive S. aureus was found in raw, unflavoured and flavoured pasteurized milk samples in a percentage of 84.04, 68.97 and 36.67 respectively based on mannitol test. With applying of multiplex PCR on S. aureus isolates which were positive with mannitol test, all S. aureus isolates were positive encoding 16s rRNA gene but that encoding nuc gene were found in raw, unflavoured and flavoured pasteurized milk samples in a percentage of 74.05, 50.00 and 45.45 respectively. Isolates positive Ý- lactamase inhibitors were found in raw, unflavoured and flavoured pasteurized milk samples in a percentage of 41.88, 90.00 and 100.00 respectively, while that positive MRSA were found in a percentage of 29.06, 20.00 and 0.00 respectively. The percentage of positive isolates for toxin production was (8.1) of SEE toxin and (2.7) of SEC toxin. By applying statistical study for sensitivity and specificity of the previous tests, Sensitivity and specificity of coagulase, Ý-hemolytic, mannitol and staphytect plus tests were 100% and 50% respectively, while TNase was 62.5% sensitivity and the highest 100% specificity. The percent of unacceptable samples were 68.00% and 10.00% in raw and pasteurized milk samples respectively based on Egyptian standards

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