Studies on Staphylococci Isolated from Bovine Mastitis: III. Activity of Penicillins and Gentamicin to Isolates |
Cheong-kyu Park |
Department of Veterinary Medicine, College of Agriculture, Gyeongbug National University |
젖소 유방유래(乳房由來) 난포구원(蘭葡球園)에 관한 연구(硏究) : III. 분리균주(分離菌株)에 대한 Penicillins 및 Gentamicin의 항균효과(抗菌效果) |
박청규 |
경북대학교 농과대학 수의학과 |
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Abstract |
The in vitro activity of penicillins(penicillin G, ampicillin, carbenicillin, methicillin and cloxacillin) and gentamicin to Staphylococcus aureus and coagulase-negative staphylococci isolated from bovine mastitic milk samples was determined. The growth of all isolates of staphylococci tested was inhibited by cloxacillin and methicillin at a concentration of $0.78{mu}g/ml$ and by gentamicin at a minimum inhibitory concentration (MIC) of $1.56{mu}g/ml$. Of the 140 strains of Staphylococcus aureus isolated 99(70.7%) gave positive reactions for penicillinase on the starch-iodine test. Of 121 isolates of coagulase-negative staphylococci, 58(47.9%) showed penicillinase production, but all the Staph. xylosus lacked the ability to produce penicillinase. MIC of penicillin G of the penicillinase-positive strains was $0.2{mu}g/ml$ or more. The combination of cloxacillin with gentamicin showed a synergistic effect by inhibiting regrowth of the tested organism. |
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