Study on antibiotic resistance and frequency of somegenes of biofilm production in staphylococcus aureusisolated from mastitis of cow

staphylococcus aureus is one of the most important bacterial cause of infectious mastitis is usually have reversible nature,chronic and resistant to treatment.one of the most convincing theories offered for the lack of effectiveness of antibiotic regimens in the treatment of S. aureus mastitis is both ability to build virulence factors and ability to generate and growth in structures called biofilms in infected tissues that can lead to resistance to most antibiotics.this research done on milk samples from 20 cows with clinical S.aureus mastitis.the result of antibiogram test are showed 100% resistance to antibiotics penicillin,cloxacillin,kanamycin,neomycin and streptomycin against revealed 100% susceptibility to antibiotics Enrofloxasin,Gentamicin,novobiocin,cobactan,nafpenzal,ceftiofor,florophenicol,lincospectin,   TETRA-DELTA  and gentamox.antibiotic susceptibility to antibiotics Tylosin,lincomycin,soltrim,trimethoprim sulfamethoxazol,tetracycline,ampicillin, and amoxicillin,respectively was  60, 0, 70 ,70, 0, 0, and 45% .about prevalence of fib, fnbB and bap genes that are involved in biofilm formation,results respectively to 85, 80 , 65 and 0% showed.the results indicate high ability of S.aureus in biofilm formation and resistance to antibiotics categories Beta-lactam and aminoglycosides.