'Flexibacter columnaris': first description in France and comparison with bacterial strains from other origins

Three strains of gliding bacteria resembling a known fish pathogen, Flexibacter columnaris, were recently isolated from diseased freshwater fishes in France. Morphological, physiological, and biochemical characteristics were very similar to those of 6 F. columnaris strains previously identified in other countries and used here for reference. This is the first unequivocal identification of this fish pathogen in France. Characteristics of this organism that distinguish it from other, apparently nonpathogenic, gliding bacteria of fish origin include its strongly adherent and rhizoid, yellow, flat colonies on solid media; its absorption of Congo red dye, and its production of flexirubin-type pigments. Other useful distinguishing characteristics are the production of H2S and the reduction of nitrates, the absence of action on any carbohydtates, the rapid and intense hydrolysis of lecithin, and the absence of growth in media containing more than 0.5 % NaCI.