Phenotypic and genotypic characterization of Flavobacterium psychrophilum from Finnish fish farms

Finnish isolates (n = 37) of Flavobacterium psychrophilum isolated from far med salmonids were studied using phenotypic and genotypic characteristics. The characteristics of isolates were compared with the characteristics of S wedish and Estonian F. psychrophilum isolates and the type strain, F. psych rophilum NCIMB 1947(T). Multiple isolates from eight disease outbreaks were examined to determine differences between isolates from a single outbreak. The F. psychrophilum isolates represented a biochemically homogeneous grou p., However, some minor differences in biochemical and physiological charac teristics were observed. Seven different antigenic patterns among Finnish i solates were detected and the results suggest a new serotype of F. psychrop hilum. Using CIA HaeIII and PvuII restriction enzymes in ribotyping analyse s 13 different genotypes were demonstrated and a possible relationship betw een serotype Fd and genotype F1 was determined. There were no significant d ifferences between the isolates from Finland, Estonia, Sweden and the type strain of F. psychrophilum.