Clinical, epidemiological, and microbiological features of Vibrio vulnificus biogroup 3 causing outbreaks of wound infection and bacteraemia in Israel

Background Vibrio vulnificus is a gram-negative bacterium that causes septi caemia and wound infection. Cases occur sporadically, and no previous outbr eaks due to a common source or a clonal strain have been reported. In the s ummer and autumn of 1996 and 1997, an outbreak of invasive V vulnificus inf ection occurred in Israel in people who had recently handled fresh, whole f ish purchased from artificial fish-ponds. Methods We reviewed clinical and epidemiological information, and undertook an environmental investigation to assess disease characteristics, modes of transmission, phenotypic characteristics of the bacterium, and fish-market ing policy. The clonal nature of 19 isolates was studied by biotyping, puls ed-field gel electrophoresis, and restriction-fragment length polymorphism (RFLP) analysis of a PCR fragment. Findings During 1996-97, 62 cases of wound infection and bacteraemia occurr ed. 57 patients developed cellulitis, four had necrotising fasciitis, and o ne developed osteomyelitis. In all cases, the fish were cultivated in inlan d fish-ponds. In the summer of 1996, fish-pond managers initiated a new mar keting policy, in which fish were sold alive instead of being packed in ice . Phenotypically, the isolates had five atypical biochemical test results. The isolates were non-typeable by pulsed-field gel electrophoresis, and all had the same PCR-RFLP pattern which had not been seen previously. Interpretation The cause of the outbreak was a new strain of V vulnificus, classified as biogroup 3. A new fish-marketing policy that began in 1996 ma y have exposed susceptible people to the organism.