Ribotyping of Aeromonas salmonicida subsp. salmonicida

Abstract

A collection of 124 strains of the bacterial fish pathogen Aeromonas salmonicjda subsp, salmonicida isolated from diseased salmonids in Denmark (n = 57), Norway (n = 28), Scotland (n = 20), and North America (n = 19) was characterized by ribotyping. For reference, the type strain NCMB 1102 was likewise examined. Digestion of total DNA with the enzymes EcoR1, HindIII and S m a l resulted in 2, 1 and 5 ribotypes, respectively, with a total of 6 ribotypes in combination. The type strain NCMB 1102 belonged to the most common of the ribotypes, irrespective of the enzyme used. Although Danish and North American strains were genetically very homogeneous, Norwegian and Scottish isolates showed some genetic diversity. In general, ribotyping was not found to b e applicable a s an epizootiological typing system for A. salmonjcida subsp. salmonicida due to low discnminatory power. Norwegian and Scottish strains contained a common Snlal ribotype suggesting a connection between isolates from these 2 countries.