الفهرس 
Supervision sheetOnly 14 pages are availabe for public view
 |  | from | 247 |  |  |
| | | from | 247 | | |
Abstract
In this study a total number of 220 raw bovine milk samples (150 from buffaloes and 70 from cows) were collected from different farms, samples from buffaloes were identified as 35 normal milk samples,90 subclinically mastitic milk samples and 25 clinically mastitic milk samples, while the total 70 cow’s milk samples were identified as 45 normal milk samples, 10 subclinically mastitic milk samples and 15 clinically mastitic milk samples. the total Staphylococcus species isolates were 42(19%) from 220 raw milk samples(27 from buffaloes and 15 from cows) 66.6% from the total isolates were originated from subclinically mastitic animals, 28.6% from healthy animals and 4.8% from clinically mastitic animals, Bacterial identification indicated that CNS constituted the higher percentage 71.4% (30 isolate), while CPS isolates constituted 28.6% from the total isolates(12 isolates), S. aureus isolates constituted 26.2 % from the total isolated species, and S. intermedius 2.4%, while CNS species were identified as S. carnosus , S. capitis , S. xylosus, S. saccharolyticus and S. auricularis in a percentage of 33.3% , 23.8% , 9.5%, 2.4% and 2.4% respectively. The highest percentage of resistance against examined antimicrobial agents was recorded in penicillin 88.1%, resistance against oxacillin, tetracycline and erythromycin were 33.3%, 31% and 9.5% respectively, while isolates showed zero resistance against other examined antimicrobial agents (ampicillin-sulbectam, ciprofloxacin, gentamycin, chloramphenicol, vancomycin). Results of virulence assay showed that most of the 42 staphylococci isolates were positive for Congo red, biofilm and hemolytic activity in a percentage of 71.4%, 64.3% and 61.9% respectively. Using PCR technique, all isolates were positive for the amplification of 16S rRNA specific for staphylococci, and 26.2% (11 isolate) positive amplification of the Nuc gene specific for S. aureus, 100% of S. aureus isolates showed positive amplification of etA gene, all S. aureus isolates were enterotoxigenic with the higher incidence in seb gene (81.8%), while Sec, Sed and See represented 63.6 % each, and decreased to 45.4% for Sea.