FINGERPRINTING OF FLAVOBACTERIUM-PSYCHROPHILUM ISOLATES BY RIBOTYPINGAND PLASMID PROFILING

Flavobacterium psychrophilum is the agent of cold-water disease and ra inbow trout fry syndrome in salmonid fish worldwide. Ribosomal RNA gen e restriction patterns (ribotypes) and plasmid profiles were determine d on a collection of 85 strains isolated from different countries and fish species. Several ribotypes were obtained by using the restriction endonucleases HincII and PvuII. Computer analysis of the ribotypes re vealed that some of them were clearly associated with the fish species from which the strains were isolated, whereas no correlation with the geographical origin was found. Most of the strains harboured at least one plasmid and several different plasmid profiles were observed, eve n among strains sharing the same ribotype. These methods, used alone o r in combination with other typing techniques, can be considered power ful tools for the epidemiological tracing of F. psychrophilum infectio ns.