[Serogroups, virulence and hemolytic activity of Aeromon as hydrophila which caused fish bacterial septicaemia].

A new infected disease called bacterial septicaemia occurred in cyprinid fish throughout China during 1989-1992. A. hydrophila was known as the most important pathogen of this harmful disease. Thirty-three strains of A. hydrophila, most isolated from moribund fishes, were serogrouped by tube-agglutination with rabbit antisera. Most of the isolates could be grouped into two serotypes, TPS-30 and PBJS-76. These two groups could be found not only in Zhejiang province but in other province in south China. It can be concluded that the two serogroups were the main Aeromonas groups caused this fish disease. These isolates were virulent to Carassius auratus, with LD50 values of 10(4) to 10(6). The hemolytic activity ranged from titers of 1/8 to 1/16. No relationship were observed with the hemolytic activity and virulence.