الفهرس 
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Abstract
Contamination of meat products with Staphylococci, mainly S. aureus, and MRSA constitutes serious problems for consumers, therefore, the present study was carried out on 150 random samples of chicken meat products viz: sausage, luncheon, and burger (50 of each), collected from different supermarkets and groceries located in Benha, Toukh and Qalub cities in Qalubiya governorate in order to detect the prevalence of Staphylococci with special reference to S. aureus. In addition, antibiotic sensitivity test was conducted on S. aureus isolates. Out of the detected antibiotic multi-resistant isolates, phenotypic and molecular characterization of enterotoxigenic MRSA strains was performed.
the obtained results showed total prevalence of staphylococci and S. aureus contaminating 26.6 and 11.3% of the examined samples. in addition, the results of bacteriological examination of the examined burger, luncheon and sausage samples revealed that the mean value of Staphylococcus and S. aureus counts were 7.3x10 and 4.5x102, 1.3x103 and 3.4x102, 2.1x103 and 6.7x102 CFU/g, respectively; with prevalence of 20% and 8%, 24% and 10%, 36% and 16%, respectively. In details, the collected samples from Qalub city revealed the highest prevalence of staphylococci and S. aureus with prevalence of 33.3 and 20%, 33.3 and 13.3%, 46.6 and 20% of positive burger, luncheon and sausage samples, respectively. Statistical analysis of variance showed significant differences, when (P≤0.05), between sausage samples particularly and the other examined meat products (luncheon and burger).
Referring to the obtained results, sausage samples showed the highest prevalence of staphylococci and S. aureus, followed by luncheon and burger samples, respectively.
Regarding with phenotypical detection of MRSA strains, the 17 S. aureus isolates were cultured on ORSAB agar for detection of MRSA strains which appeared as deep blue colored colony. Referring to the obtained results, out of the examined seventeen isolates, seven isolates appeared to be MRSA strains on ORSAB agar, which were furtherly examined for antibiotic sensitivity.
In addition, the in- vitro sensitivity test for the isolated S. aureus (7 isolates) showed resistance to amoxicillin, ampicillin, cefotaxime, oxacillin, ciprofloxacin, erythromycin, gentamicin, levofloxacin, norfloxacin and trimethoprim/ sulphamethoxazol; while 85.7% of the examined isolates were sensitive to vancomycin.
Out of the phenotypically appeared MRSA strains, two isolates (isolated from sausage and luncheon samples collected from Toukh and Benha cities, respectively) were examined molecularly for detection of mecA gene representing MRSA strain and SEs genes representing staphylococcal enterotoxins (A, B, C, D and E). Polymerase chain reaction (PCR) figures cleared that, the mecA and staphylococcal enterotoxin type-A (SEA) were detected in both the examined isolates at 310 and 102 bp, respectively.
Finally, the present study proved that chicken meat products are considered of public health hazard due to presence of Staphylococci mainly enterotoxigenic S. aureus especially MRSA strains; this may be due to mishandling and the negligence of hygienic aspects either at production levels where most workers did not have medical certificates or selling of meat with expired dates. Moreover, the hygienic measures are suggested for obtaining meat and meat products with controlled bacterial pathogens to be fit for human consumption