Vibrio parahaemolyticus, Vibrio vulnificus, and Vibrio cholerae are Gram negative bacteria that naturally occur in marine and estuarine environment, both as free-floating cells or attached to chitinous surfaces. Although Vibrio spp. are readily isolated from the environment, not all strains are virulent. Therefore, the ability to detect the presence of vibrios is vital, but determination of pathogenicity is equally important.

The research reported here was focused on prevalence and characteristics of environmental Vibrio species and how the environment provides a natural ecosystem for human pathogens and reservoir of virulence factors. Those objectives were achieved by carrying out intensive sampling over three years, during which water, sediment, and oyster samples were collected from the Chesapeake Bay, Maryland. Detection and molecular characterization of Vibrio parahaemolyticus and Vibrio vulnificus were done and the diversity of V. parahaemolyticus and V. vulnificus isolates from individual oyster samples was investigated. The large-scale populations of V. parahaemolyticus and V. vulnificus in the Chesapeake Bay and smaller scale populations of individual oysters were analyzed, thereby providing a snapshot of V. parahaemolyticus and V. vulnificus distribution in the environment. Because antibiotic resistance is an increasing public health concern, antibiograms of V. parahaemolyticus and V. vulnificus isolates from environmental sources were done to determine antibiotic resistance patterns in environmental isolates. Detection and enumeration of Vibrio species are a concern since Vibrio spp. can enter viable by nonculturable (VBNC) state. Thus, new and improved Vibrio detection methods are needed. This this study the Cholera O1 and O139 SMART II test were investigated for potential use in detecting V. cholerae in ballast water treatment systems.