Indole-positive Vibrio vulnificus isolated from disease outbreaks on a Danish eel farm

Vibrio vulnificus was isolated in 1996 from 2 disease outbreaks on a Danish eel farm which used brackish water. A characteristic clinical sign was extensive, deep muscle necrosis in the head region. V. vulnificus was isolated from kidney, mucus, spleen, gill and intestine of diseased eels. Thirty-two isolates were examined phenotypically and serologically for pathogenicity to eels and for correlation to ribotype and plasmid profile. Biochemically, the isolates showed properties similar to those described previously for eel-pathogenic strains of V, vulnificus, with the exception of indole production. Virulence was evaluated by LD50 (the 50 % lethal dose), which ranged from