Atypical Aeromonas salmonicida, the Causative Agent of an Ulcer Disease of Eel Occurred in Kagoshima Prefecture

Abstract

An ulcer disease occurred with high mortalities among cultured eels in various ponds in Kagoshima Prefecture between October 1982 and March 1983. The diseased eels were associated with extensive ulcerative lesions on the head and body. On the basis of the bacteriological characteristics of the isolates from diseased eels were classified into atypical Aeromonas salmonicida; the characteristics of the isolates differed from those of the subspecies of salmonicida, achromogenes, and masoucida. The biochemical characteristics of the isolates, as far as we tested, did not coincide with those of typical A. salmonicida isolated from ulcerative diseases of minnows, Phoxinus phoxinus, goldfish, Carassius auratus, Atlantic salmon, Salmo salar, and carp, Cyprinus carpio.
A common antigen was observed in our isolate, A. salmonicida subspecies salmonicida, A. salmonicida subspecies masoucida, and an atypical A. salmonicida from goldfish with ulcer disease. However, the antigen of the isolate was partially different from those of A. salmonicida suspecies masoucida and atypical A. salmonicida.
Isolates had a strong autoaggregating tendency and an additional surface “A” layer.