Vibrio, a type (genus) of rod-shaped bacteria. Some Vibrio species cause cholera in humans. Vibrio is a genus of Gram-negative bacteria possessing a curved rod shape (comma shape), several species of which can cause foodborne infection, usually associated with eating undercooked seafood. Typically found in saltwater, Vibrio spp. are facultative anaerobes that test positive for oxidase and do not form spores. All members of the genus are motile and have polar flagella with sheaths. Most disease-causing strains are associated with gastroenteritis, but can also infect open wounds and cause septicemia.