Evidence that mortality from Vibrio vulnificus infection results from single strains among heterogeneous populations in shellfish.

Vibrio vulnificus is the leading cause of food-related mortality reported in the state of Florida. It is normal microflora in marine environments, where seawater and molluscan shellfish are the primary vectors of V. vulnificus disease. Risk correlates with seasonally high numbers of V. vulnificus bacteria during the summer months. Currently, the infectious dose for humans, as well as whether the disease is caused by single or multiple strains found in molluscan shellfish, is unknown. In this work, we studied pulsed-field gel electrophoresis profiles of V. vulnificus strains isolated from blood and oysters associated with V. vulnificus disease. Results showed that ca. 10(3) V. vulnificus bacteria/gram of oyster and higher concentrations were associated with human infections and that a single V. vulnificus strain, evidenced by pulsed-field gel electrophoresis profiles, was isolated from human tissues.