養殖ハマチの類結節症に対するアンピシリンの水産薬としての応用に関する研究-I

類結節症抗菌に対するin vitroでの抗菌力,耐性獲得および耐性消失

抄録

Studies are being made to apply ampicillin for pseudotuberculosis of cultured yellowtails. In vitro sensitivity and development of drug-resistance characteristics of Pasteurella piscicida were examined. Chloramphenicol was used for comparison. The minimum inhibitory concentration of ampicillin to P. piscicida was 0.04 to 0.08 mcg/ml and the MIC of chloramphenicol was 0.63 mcg/ml. Antibacterial activity of ampicillin was 8 to 16 times greater than the activity of chloramphenicol. After 10 serial passages in vitro under the presence of drug, MIC values to ampicillin and to chloramphenicol were 4 to 8 times greater than the initial values. Reversion of acquired drug-resistance features to ampicillin also was studied. After 5 serial passages in vitro in BHI agar under the absence of the drug, the acquired drug-resistance characteristics of P. piscicida disappeared, i.e., MIC changing from 0.32 mcg/ml to 0.04-0.08 cmg/ml. Results of the study suggest that ampicillin is an useful antibacterial drug for pseudotuberculosis of cultured yellowtails.