A high prevalence of tylosin resistance among aureus strains isolated from bovine mastitis.

The macrolides appear to have considerable effects for treatment of bovine mastitis because of excellent diffusion into the mammary gland, long half-life, low protein binding, high intracellular concentration and lipid solubility. Acquired resistance to macrolides in is primarily related to target-site modification through acquisition of an gene. In the present study the prevalence of both phenotypic and genotypic tylosin resistance in isolates (n = 103) from subclinical mastitis in nine dairy farms belonging to three different province of Iran were investigated.