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 species 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).
Several species of Vibrio are pathogens. Most disease-causing strains are associated with gastroenteritis, but can also infect open wounds and cause septicemia. They can be carried by numerous marine animals, such as crabs or prawns, and have been known to cause fatal infections in humans during exposure. Pathogenic Vibrio species include V. cholerae (the causative agent of cholera), V. parahaemolyticus, and V. vulnificus. V. cholerae is generally transmitted by contaminated water. Pathogenic Vibrio species can cause foodborne illness (infection), usually associated with eating undercooked seafood.
V. 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. As of 2013 in the United States, Vibrio infections as a whole were up 43% when compared with the rates observed in 2006-2008. V. vulnificus, the most severe strain, has not increased. Foodborne Vibrio infections are most often associated with eating raw shellfish.
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 nonhuman sources are not hemolytic.
Many Vibrio species are also zoonotic. They cause disease in fish and shellfish, and are common causes of mortality among domestic marine life.
Medical care depends on the clinical presentation and the presence of underlying medical conditions.
Because V. gastroenteritis is self-limited in most patients, no specific medical therapy is required. Patients who cannot tolerate oral fluid replacement may require intravenous fluid therapy.
Although most Vibrio species are sensitive to antibiotics such as doxycycline or quinolones, antibiotic therapy does not shorten the course of the illness or the duration of pathogen excretion. However, if the patient is ill and has a high fever or an underlying medical condition, oral antibiotic therapy with doxycycline or quinolone can be initiated.
Noncholera Vibrio infections
Patients with noncholera Vibrio wound infection or septicemia are much more ill and frequently have other medical conditions. Medical therapy consists of:
- Prompt initiation of effective antibiotic therapy (doxycycline or a quinolone)
- Intensive medical therapy with aggressive fluid replacement and vasopressors for hypotension and septic shock to correct acid-base and electrolytes abnormalities that may be associated with severe sepsis
- Early fasciotomy within 24 hours after development of clinical symptoms can be life-saving in patients with necrotizing fasciitis.
- Early debridement of the infected wound has an important role in successful therapy and is especially indicated to avoid amputation of fingers, toes, or limbs.
- Expeditious and serial surgical evaluation and intervention are required because patients may deteriorate rapidly, especially those with necrotizing fasciitis or compartment syndrome.
- Reconstructive surgery, such as skin graft, is indicated in the recovery phase.
V. harveyi is a pathogen of several aquatic animals, and is notable as a cause of luminous vibriosis in shrimp (prawns)
The "typical", early-discovered Vibrio species, 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 directions (peritrichous), and the other species, such as V. fischeri, have tufts of polar flagella with sheath (lophotrichous).
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- Vibrio genomes and related information at PATRIC, a Bioinformatics Resource Center funded by NIAID
- Bacteriological Analytical Manual Online
- Association of Vibrio Biologist