DAO 33:167-177 (1998)  -  doi:10.3354/dao033167

Fingerprinting of Flavobacterium psychrophilum isolates by ribotyping and plasmid profiling

Chehid Chakroun1, Francine Grimont2, Maria C. Urdaci3, Jean-François Bernardet1,*

1Unité de Virologie et Immunologie Moléculaires, Institut National de la Recherche Agronomique, F-78352 Jouy-en-Josas Cedex, France
2Unité des Entérobactéries, Unité 389 de l'Institut National de la Santé et de la Recherche Médicale, Institut Pasteur, F-75724 Paris Cedex 15, France
3Laboratoire de Microbiologie, Ecole Nationale des Ingénieurs des Travaux Agricoles de Bordeaux, 1 cours du Général de Gaulle, BP 201, F-33175 Gradignan Cedex, France
*Addressee for correspondence. E-mail:

ABSTRACT: Flavobacterium psychrophilum is the agent of cold-water disease and rainbow trout fry syndrome in salmonid fish worldwide. Ribosomal RNA gene restriction patterns (ribotypes) and plasmid profiles were determined 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 revealed 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, even among strains sharing the same ribotype. These methods, used alone or in combination with other typing techniques, can be considered powerful tools for the epidemiological tracing of F. psychrophilum infections.

KEY WORDS: Flavobacterium psychrophilum · Cold-water disease · Rainbow trout fry syndrome · Ribotyping · Plasmid profiling · Epidemiology

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