Vibrio

Vibrio is a genus of Gram-negative bacteria possessing a curved rod shape. Typically found in saltwater, Vibrio 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 sheath. Recent phylogenies have been constructed based on a suite of genes (multi-locus sequence analysis).

Pathogenic strains
Several species of Vibrio include clinically important human pathogens. Most disease causing strains are associated with gastroenteritis but can also infect open wounds and cause septicemia. It can be carried by numerous sea living animals, such as crabs or prawns, and has been known to cause fatal infections in humans during exposure. Pathogenic Vibrio include V. cholerae (the causative agent of cholera), V. parahaemolyticus, and V. vulnificus. Vibrio cholerae is generally transmitted via contaminated water. Pathogenic Vibrio are can cause food poisoning, usually associated with eating undercooked seafood.

Vibrio vulnificus outbreaks commonly occur in warm climates and small, generally lethal, outbreaks occur regularly. An outbreak occurred in New Orleans after Hurricane Katrina and several lethal cases occur most years in Florida.

V. parahaemolyticus is also associated with the Kanagawa phenomenon, in which strains isolated from human hosts (clinical isolates) are hemolytic on blood agar plates, while those isolated from non-human sources are non-hemolytic.

Many Vibrio are also zoonotic. They cause disease in fish and shellfish, and are common causes of mortality among domestic marine life.

Other strains
Vibrio fischeri, Photobacterium phosphoreum, and V. harveyi are notable for their ability to communicate. Both V. fischeri and Ph. phosphoreum are symbiotes of other marine organisms (typically jellyfish, fish, or squid), and produce light via bioluminescence through the mechanism of quorum sensing. Vibrio harveyi is a pathogen of several aquatic animals and notable as a cause of luminous vibriosis in shrimps (prawns)

Flagella
The "typical", early-discovered vibrio such as V. cholerae have a single polar flagellum (monotrichous) with sheath. Some species such as V. parahaemolyticus and V. alginolyticus have both a single polar flagellum with sheath and thin flagella projecting in all direction (peritrichous), and the other species such as V. fischeri have tufts of polar flagella with sheath (lophotrichous).