الفهرس 
List of ContentsOnly 14 pages are availabe for public view
 |  | from | 161 |  |  |
| | | from | 161 | | |
Abstract
One important feature of Staphylococcaureus virulence is due to its ability to attack the cell membrane of host cell with alarge array of membrane damaging toxins and peptides such as hemolysins. Therefore, this study was undertaken to perform phynotypic and gynotypic characterization of S.aureushemolysins isolated from milk of cows with clinical mastitis. A total of 173 milk samples were collected from two dairy farms and were subjected to bacteriological isolation procedures, 55 S.aureus isolates have been recovered with a percentage of 31.79%. S.aureus isolates were evaluated for their Alpha(α) and beta (β)hemolysins production on sheep and bovine blood agar. Alphahemolysinwere detected in 50 (90.90%) strains, betahemolysin were detected in 47 (85.45%) strains either alone or in combined form. However, non-hemolytic S.aureus strains were detected in 5 (9.09%) strains. On titration, α-toxins titre were much more than that for β-toxins. Based on PCR results, the overall prevalence rate ofhla gene was higher thanhlb gene and these results were correlated with their phynotypic hemolytic activity on blood agar plates. In conclusion, the high prevalence rate of alpha and beta hemolysis in S.aureus isolated from mastitis suggests the hemolysins could have significant role in pathogenesis of mastitis, in addition, the capability of S.aureus strains to produce alpha and betahemolysin indicates that these toxins might be necessary for establishment of the S.aureus in mammary glands.