BIOCHEMICAL AND PHYSIOLOGICAL-CHARACTERISTICS AND PLASMID PROFILES OF AEROMONAS-HYDROPHILA STRAINS, ISOLATED FROM FRESH-WATER FISH AND FROM FRESH-WATER

Twenty-five Aeromonas hydrophila strains, isolated from freshwater fish and from freshwater samples were identified, using API 20NE and CH50. They were screened for the presence of plasmids. A group of 10 strains was found without plasmids, 11 strains harbored one plasmid (20 kb), and a third group (four strains) contained two or three plasmids. A 20 kb plasmid was common to all plasmid-positive strains. Although their plasmid profile differs, all groups are very similar with regard to their biochemical and physiological characterization. However, the differences observed using clustering can be explained by characteristics, some of which have been reported as virulence associated. No relationship between these factors and the presence of plasmids is found. The possibility of differentiating A. hydrophila strains on the basis of biochemical characteristics using a cluster analysis is considered.