Drug Resistance of Vibrio anguillarum Isolated from Ayu between 1989 and 1991.

Abstract

One hundred and fourteen strains of Vibrio anguillarum collected from cultured ayu Plecoglos-sus altivelis between 1989 and 1991 were studied for their sensitivities to 10 chemotherapeutants. Among the drugs tested florfenicol (FF) was the most effective against all strains. Only one strain was found to be sensitive to all the drugs (ampicillin, chloramphenicol (CP), FF, furazolidone, kanamycin (KM), nalidixic acid, streptomycin (SM), sulfamonomethoxine (SA), tetracycline (TC), and trimethoprim (TMP). The remaining strains showed resistance to various combinations of drugs. Transferable R plasmids were detected from 21 strains encoded with resistance to 7 to 9 drugs. All detected R plasmids encoded with resistance to CP, KM, SA, SM, TC, and TMP. Identical endonuclease digestion patterns were observed in R plasmids detected from various areas, and strong homology among these R plasmid DNAs were also observed. The DNA structure of the R plasmids detected from 1989 to 1991 was not similar to that of previously detected R plasmids from V. anguillarum. The results indicate that multiple drug resistant strains of V. anguillarum were common in ayu farms between 1989 and 1991.