Antimicrobial resistance of Staphylococcus aureus isolated from bovine mastitis in China.

Mastitis is one of the largest production concerns in the dairy industry worldwide. Mastitis caused by Staphylococcus aureus is a major concern to the dairy industry because of its resistance to antibiotic treatment. In this report, the results of antibiotic susceptibility test, carried out on 236 Staphylococcus aureus isolated from milk samples which were collected from cases of mastitis in cow herds of China, are presented. The regions and number of isolates include Inner Mongolia (112), Hebei (58) and Heilongjiang (66). Susceptibility to ampicillin, penicillin G, amoxicillin, piperacillin, cephalexin, cephazolin, cefotaxime, ceftazidime, cefoxitin, SMZ-TMP, gentamycin, kanamycin, norfloxacin, ciprofloxacin, ofloxacin, furaxone, torlamician, roxithromycin, clindamycin and vancomycin was determined by the disc diffusion method. Antibiotic susceptibility testing showed 87.30% (206 of 236) isolates were resistant to penicillin G. This result compares with the reports from other countries; the overall level of resistance was generally high for all antimicrobial agents tested.