Vibrio is a genus of Gram-negative bacteria possessing a curved rod 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. Recent phylogenies have been constructed based on a suite of genes (multilocus sequence analysis). The name Vibrio derives from Filippo Pacini who isolated microorganisms he called "vibrions" from cholera patients in 1854, because of their motility. Vibrio ordalii is a Gram-negative, short curve rod-shaped, motile by single polar flagellum and facultative anaerobic bacterium. It is the causative agent of vibriosis which is characterized by the presence of skin lesions, haemorrhaging ulcers, serious leukopenia and a high mortality in salmonid and non-salmonid species.