VIBRIO PARAHAEMOLYTICUS–ISOLATION, IDENTIFICATION, CLASSIFICATION, AND ECOLOGY1

Abstract

Vibrio parahaemolyticus was isolated from samples of water, sediment, blue crabs, oysters, and clams collected in several areas of Chesapeake Bay. Numerical taxonomy was used to identify and classify the bacterial isolates. Deoxyribonucleic acid (DNA) base composition, serology, isozyme, gas chromatography, bacteriophage sensitivity, and DNA/DNA reassociation analyses confirmed the identification and classification of V. parahaemolyticus and permitted establishment of genetic relationships of the Chesapeake Bay strains with isolates from victims of food poisoning in Japan and from samples taken in geographically diverse areas of the United States. Isolates implicated in recent outbreaks of food poisoning, the first fully documented cases of V. parahaemolyticus food poisoning in the United States, were shown by DNA/DNA reassociation measurements to be closely related to the Japanese and other isolates collected in the United States. Fatty acid profiles of cell derivatives prepared using GLC were useful in diagnosing Vibrio spp., including V. parahaemolyticus and Vibrio cholerae. Bacteriophages isolated from ocean sediments collected off Cape Hatteras were found to be active against V. cholerae and V. parahaemolyticus. Distribution of V. parahaemolyticus appears to be restricted to coastal and estuarine regions. V. parahaemolyticus has been shown to be closely associated with zooplankton and a life cycle for V. parahaemolyticus in Chesapeake Bay is proposed.