The minimum inhibitory concentration (MIC) of five chemotherapeutic agents (penicillin, streptomycin, tetracycline, oxytetracycline and furazolidone) was measured for 126 strains of Staphylococcus aureus isolated from the udder of dairy cattle.
The results obtained were as follows:
1. The MIC of penicillin, streptomycin, tetracycline, oxytetracycline and furazolidone ranged from 0.03 to 32 ㎍/㎖, 0.06 to 128㎍/㎖, 0.06 to 128㎍/㎖, 1.0 to 512㎍/㎖, and 0.06 to 32㎍/㎖, respectively. The most frequent MIC of the above drugs were; penicillin 0.5㎍/㎖, streptomycin 1.0ug㎍/㎖, tetracycline 0.5㎍/㎖, oxytetracycline 4.0㎍/㎖, and furazolidone 2.0㎍/㎖.
2. The number of strains resistant to penicillin, streptomycin, tetracycline and oxytetracycline were 89(77.6), 9(7.1%), 10(7.9%), and 26(20.6%), respectively. Twenty-eight (29.2%) strains showed multiple resistance to more than two antibiotics tested.
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