Drug Sensitivity of Pasteurella pisicida Isolated from Cultured Yellowtail from 1986 to 1988

Abstract

The in vitro antibacterial activity of six chemotherapeutic agents against Pasteurella piscicida was determined. Three hundred and six strains of P. piscicida were isolated from diseased cultured yellowtail Seriola quinqueradiata from 1986 to 1988. Susceptibilities to six chemotherapeutic agents were examined as the minimum inhibitory concentration (MIC), using the method of the Japan Society of Chemotherapy. Resistance to ampicillin (ABPC) and amoxicillin (AMPC) was found in 35% of the strains. Resistance to oxolinic acid (OA) and flumequine (FM) was found in 37% of the strains. High antibacterial activity was demonstrated by novobiocin (NB) and flor-fenicol (FF) and moderatedly high activity by sodium nifurstyrenate (NFS-Na). However, the MIC of NFS-Na varied between 0.2μg/ml and 12.5μg/ml. The resistance pattern could be divided into three groups: the first group was resistant to ABPC and AMPC; the second group was re-sistant to OA and FM; the third group was resistant to ABPC, AMPC, OA and FM. The third group comprised 23% of the strains.