Detection of potential virulence markers of Vibrio vulnificus strains isolated from fish in Sweden.

A variety of potential virulence markers such as the production of cytotoxin, haemolysin, exoenzymes, bactericidal action of sera, presence of capsule and adhesion to human intestinal cells were investigated on Vibrio vulnificus strains isolated from eels in Sweden. The strains had the capacity of producing all or some of the above-mentioned virulence markers, to varying degrees though none of the strains produced any capsule. The strains also bound specifically to human intestinal cells in vitro with maximum adhesion levels of 30 bacteria/cell. The results on binding of V. vulnificus cytotoxin to HeLa cells, showed that a very short exposure time (30 min) was required for inducing the cytotoxic effects. V. vulnificus is a relatively new addition to the list of bacteria pathogenic for humans, and since there are increasing reports on its isolation from aquatic environments and seafood (e.g. raw oysters, crabs and shellfish), the results on virulence profiles of V. vulnificus strains presented above emphasize the importance of these organisms in public health and epidemiological studies.