Abstract: The assay was aimed to establish and verify the sterility test for cloxacillin benzathine intramammary infusion. Centrifugation-membrane filtration-enzyme neutralization method were used and verified on the basis of the appendix to Veterinary Pharmacopoeia of the People's Republic of China (2010 edition). The results showed that the antibacterial activity of various strains could be eliminated with centrifugation-membrane filtration-enzyme neutralization method which needed at least 3 million units penicillinase and 400 mL 0.5% polysorbate-80 sodium chloride (pH 7.0)-peptone buffer solution as flushing fluid. In validation test, all the test strains grew well and bacteria was not found in the tube of test sample. The results showed that centrifugation-membrane filtration-enzyme neutralization method was an accurate and reliable method, and could be used for sterility test of cloxacillin benzathine intramammary infusion.

Key words: cloxacillin benzathine; intramammary infusion; membrane filtration method; sterility test