Detection of R Plasmids in Naturally Occurring Fish‐Pathogenic Bacteria, Edwardsiella tarda

The conjugative R plasmids were detected from fish-pathogenic Edwardsiella tarda isolated from cultured eels. These R plasmids were resistant to sulfonamide and tetracycline, or sulfonamide, streptomycin, chloramphenicol, tetracycline and kanamycin. There were no inhibitions in growth of phages W-31, P1, T1, T3, T7, and lambda. They were classified into incompatibility group A.