Vibrio is a genus of Gram-negative bacteria, possessing a curved-rod (comma) shape, [1] [2] [3] [4] several species of which can cause foodborne infection or soft-tissue infection called Vibriosis. Infection is commonly associated with eating undercooked seafood. Being highly salt tolerant and unable to survive in freshwater, Vibrio spp. are commonly found in various salt water environments. Vibrio spp. are facultative anaerobes that test positive for oxidase and do not form spores. [4] [5] All members of the genus are motile. They are able to have polar or lateral flagellum with or without sheaths. [4] [6] Vibrio species typically possess two chromosomes, which is unusual for bacteria. [7] [8] Each chromosome has a distinct and independent origin of replication, [9] and are conserved together over time in the genus. [10] Recent phylogenies have been constructed based on a suite of genes (multilocus sequence analysis). [1]
O. F. Müller (1773, 1786) described eight species of the genus Vibrio (included in Infusoria), three of which were spirilliforms. [11] Some of the other species are today assigned to eukaryote taxa, e.g., to the euglenoid Peranema or to the diatom Bacillaria . However, Vibrio Müller, 1773 became regarded as the name of a zoological genus, and the name of the bacterial genus became Vibrio Pacini, 1854. [12] Filippo Pacini isolated micro-organisms he called "vibrions" from cholera patients in 1854, because of their motility. [13] In Latin "vibrio" means "to quiver". [14]
The genus Vibrio contains a large number of species, and these vary somewhat in their biochemical characteristics. Colony, morphological, physiological, and biochemical characteristics of the genus Vibrio are shown in the Table below. [4]
Test type | Test | Group-1 | Group-2 |
---|---|---|---|
Colony characters | Size | Medium | Medium |
Type | Round | Round | |
Color | Whitish | Whitish | |
Shape | Convex | Convex | |
Morphological characters | Shape | Curved-rod | Curved-rod |
Physiological characters | Motility | + | + |
Growth at 6.5% NaCl | + | + | |
Biochemical characters | Gram’s staining | – | – |
Oxidase | + | + | |
Catalase | + | + | |
Oxidative-Fermentative | Fermentative | Oxidative | |
Motility | + | + | |
Methyl Red | + | – | |
Voges-Proskauer | + | – | |
Indole | – | – | |
H2S Production | – | + | |
Urease | – | + | |
Nitrate reductase | – | + | |
β-Galactosidase | + | + | |
Hydrolysis of | Gelatin | + | + |
Aesculin | – | + | |
Casein | – | + | |
Tween 40 | + | + | |
Tween 60 | + | + | |
Tween 80 | + | + | |
Acid production from | Glycerol | + | + |
Galactose | – | + | |
D-Glucose | + | + | |
D-Fructose | + | V | |
D-Mannose | + | V | |
Mannitol | + | V | |
N-Acetylglucosamine | + | + | |
Amygdalin | + | – | |
Maltose | + | + | |
D-Melibiose | – | – | |
D-Trehalose | + | – | |
Glycogen | + | + | |
D-Turanose | + | + |
Note: Group-1: Vibrio alginolyticus; Group-2: Vibrio natriegens, Vibrio pelagius, Vibrio azureus; + = Positive; – =Negative; V =Variable (+/–)
Several species of Vibrio are pathogens. [15] Most disease-causing strains are associated with gastroenteritis, but can also infect open wounds and cause sepsis. [16] They can be carried by numerous marine animals, such as crabs or prawns, and have been known to cause fatal infections in humans after exposure. [17] Risk of clinical disease and death increases with certain factors, such as uncontrolled diabetes, elevated iron levels (cirrhosis, sickle cell disease, hemochromatosis), and cancer or other immunocompromised states. Pathogenic Vibrio species include V. cholerae (the causative agent of cholera), V. parahaemolyticus , and V. vulnificus.V. cholerae is generally transmitted by contaminated water. [3] Pathogenic Vibrio species can cause foodborne illness (infection), usually associated with eating undercooked seafood. [18] When ingested Vibrio bacteria can primarily result in watery diarrhea along with other secondary symptoms. [19] The pathogenic features can be linked to quorum sensing, where bacteria are able to express their virulence factor via their signaling molecules. [20]
V. vulnificus outbreaks commonly occur in warm climates and small, generally lethal, outbreaks occur regularly. An outbreak occurred in New Orleans after Hurricane Katrina, [21] and several lethal cases occur most years in Florida. [22] 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. [23]
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. [24]
Many Vibrio species are also zoonotic. They cause disease in fish and shellfish, and are common causes of mortality among domestic marine life.
A common sign of Vibrio infection is cholera. Cholera primarily presents with rapid water loss by watery diarrhea. Other symptoms include vomiting and muscle cramps. [25] Water loss can lead to dehydration which can be mild to moderate to severe. Moderate to severe dehydration requires immediate treatment. V. cholerae is the most common pathogen that causes cholera. The gold standard for detecting cholera is through cultures of stool samples or rectal swabs. Identification is then done through microscopy or by agglutination of antibodies. [25] Cultures are done in thiosulfate citrate bile-salts sucrose agar. V cholerae will form yellow colonies. [26]
Vibriosis is a sign of a more severe Vibrio infection. Common causes of vibriosis include consumption of raw or undercooked seafood, primarily oysters, or wound exposure to sea water. The majority of V. parahaemolyticus infections can be self-limiting and symptoms include diarrhea, nausea, headaches, fever and chills. V. vulnificus can lead to a more serious disease, particularly in wound infection which can turn into necrotizing fasciitis. V. parahaemolyticus is the most common pathogen in vibriosis, however V. vulnificus is more common in people who have certain risk factors like older age, liver disease or diabetes mellitus. Like all vibrio diagnosis, vibriosis can also be determined in stool cultures. V. parahaemolyticus and V. vulnificus will form green colonies. [26]
Medical care depends on the clinical presentation and the presence of underlying medical conditions.
Because Vibrio gastroenteritis is self-limited in most patients, no specific medical therapy is required. [27] Patients who cannot tolerate oral fluid replacement may require intravenous fluid therapy.
Although most Vibrio species are sensitive to antibiotics, such as doxycycline or ciprofloxacin, 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 ciprofloxacin can be initiated. [27]
Patients with non-cholera Vibrio wound infection or sepsis are much more ill and frequently have other medical conditions. Medical therapy consists of:
The most effective method to prevent cholera is the improvement of water and food safety. This includes the sanitation of water, proper preparation of food and community awareness of outbreaks. Prevention has been most effective in countries where cholera is endemic.
Another method is cholera vaccines. Examples of cholera vaccines include Dukoral and Vaxchora. [28]
Prevention of vibriosis is mostly effective in food processing. Food items, mostly seafood, that commonly contain vibrio organisms are regularly controlled. The water that seafood is fished or farmed from is analyzed to determine microorganism content. Food processing methods like pasteurization and high pressure are used to eliminate microorganisms and pathogens. [26]
V. harveyi is a pathogen of several aquatic animals, and is notable as a cause of luminous vibriosis in shrimp (prawns). [29] Aliivibrio fischeri (or V. fischeri) is known for its mutualistic symbiosis with the Hawaiian bobtail squid, which is dependent on microbial luminescence. [30]
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). [31]
Typical bacterial flagellum structure contains three components: the basal body, the hook and the filament. Like typical bacteria, Vibrio spp, have these three components, but with increased complexity in the basal body. In addition, Vibrio spp. use five or six distinct flagellum subunits to construct the flagellar filament, rather than the single flagellin found in many other bacteria. In Vibrio spp, most have a single flagellum located on one pole of the bacterium, although some species have additional flagella in peritrichous or lophotrichous arrangements. Another difference is that the gradient used to power the flagellar motor is sodium driven rather than proton driven; this creates greater torque, and Vibrio flagella have been shown to rotate over five times faster than the H+-driven flagella of E. coli. The flagellum is also surrounded by a sheath extending from the membrane. The purpose of this sheath has yet to be determined. [32]
Motility is very important for Vibrio spp for infection. Research has shown that a variety of Vibrios mutants that are defective in flagella synthesis or non-motile are defective in infection. Loss of motility in Vibrio has shown impaired colonization and adherence to host's intestines. [32]
Natural transformation is a common bacterial adaptation for DNA transfer that employs numerous bacterial gene products. [33] [34] For a recipient bacterium to bind, take up, and recombine exogenous DNA into its chromosome, it must become competent, that is, enter a special physiologic state. The DNA-uptake process of naturally competent V. cholerae involves an extended competence-induced pilus and a DNA-binding protein that acts as a ratchet and reels DNA into the periplasm. [35] Natural transformation has also been described for V. fischeri, [36] V. vulnificus [37] and V. parahaemolyticus. [38]
V. cholerae has been used in discoveries of many bacterial small RNAs. Using sRNA-Seq and Northern blot candidate sRNAs were identified and characterised as IGR-sRNA (intragenic region), AS-sRNAs (transcribed from the antisense strand of the open reading frame (ORF) and ORF-derived. [39] One of the candidates from this study, IGR 7, was shown to be involved in carbon metabolism and later renamed MtlS RNA. Other sRNAs identified in V. cholerae through genetic screens and computational methods include Qrr RNA, Vibrio regulatory RNA of OmpA, MiX sRNA, Vibrio cholerae ToxT activated RNAs, foR RNA, and VqmR sRNA.
Cholera is an infection of the small intestine by some strains of the bacterium Vibrio cholerae. Symptoms may range from none, to mild, to severe. The classic symptom is large amounts of watery diarrhea lasting a few days. Vomiting and muscle cramps may also occur. Diarrhea can be so severe that it leads within hours to severe dehydration and electrolyte imbalance. This may result in sunken eyes, cold skin, decreased skin elasticity, and wrinkling of the hands and feet. Dehydration can cause the skin to turn bluish. Symptoms start two hours to five days after exposure.
A flagellum is a hairlike appendage that protrudes from certain plant and animal sperm cells, from fungal spores (zoospores), and from a wide range of microorganisms to provide motility. Many protists with flagella are known as flagellates.
Vibrio cholerae is a species of Gram-negative, facultative anaerobe and comma-shaped bacteria. The bacteria naturally live in brackish or saltwater where they attach themselves easily to the chitin-containing shells of crabs, shrimp, and other shellfish. Some strains of V. cholerae are pathogenic to humans and cause a deadly disease called cholera, which can be derived from the consumption of undercooked or raw marine life species or drinking contaminated water.
Campylobacter is a type of bacteria that can cause a diarrheal disease in people. Its name means "curved bacteria", as the germ typically appears in a comma or "s" shape. According to its scientific classification, it is a genus of gram-negative bacteria that is motile.
El Tor is a particular strain of the bacterium Vibrio cholerae, the causative agent of cholera. Also known as V. cholerae biotype eltor, it has been the dominant strain in the seventh global cholera pandemic. It is distinguished from the classic strain at a genetic level, although both are in the serogroup O1 and both contain Inaba, Ogawa and Hikojima serotypes. It is also distinguished from classic biotypes by the production of hemolysins.
Vibrio vulnificus is a species of Gram-negative, motile, curved rod-shaped (vibrio), pathogenic bacteria of the genus Vibrio. Present in marine environments such as estuaries, brackish ponds, or coastal areas, V. vulnificus is related to V. cholerae, the causative agent of cholera. At least one strain of V. vulnificus is bioluminescent. Increasing seasonal ocean temperatures and low-salt marine environments like estuaries favor a greater concentration of Vibrio within filter-feeding shellfish; V. vulnificus infections in the Eastern United States have increased eightfold from 1988–2018.
Aliivibrio fischeri is a Gram-negative, rod-shaped bacterium found globally in marine environments. This species has bioluminescent properties, and is found predominantly in symbiosis with various marine animals, such as the Hawaiian bobtail squid. It is heterotrophic, oxidase-positive, and motile by means of a single polar flagella. Free-living A. fischeri cells survive on decaying organic matter. The bacterium is a key research organism for examination of microbial bioluminescence, quorum sensing, and bacterial-animal symbiosis. It is named after Bernhard Fischer, a German microbiologist.
Vibrio harveyi is a Gram-negative, bioluminescent, marine bacterium in the genus Vibrio. V. harveyi is rod-shaped, motile, facultatively anaerobic, halophilic, and competent for both fermentative and respiratory metabolism. It does not grow below 4 °C. V. harveyi can be found free-swimming in tropical marine waters, commensally in the gut microflora of marine animals, and as both a primary and opportunistic pathogen of marine animals, including Gorgonian corals, oysters, prawns, lobsters, the common snook, barramundi, turbot, milkfish, and seahorses. It is responsible for luminous vibriosis, a disease that affects commercially farmed penaeid prawns. Additionally, based on samples taken by ocean-going ships, V. harveyi is thought to be the cause of the milky seas effect, in which, during the night, a uniform blue glow is emitted from the seawater. Some glows can cover nearly 6,000 sq mi (16,000 km2).
The Vibrionaceae are a family of Pseudomonadota given their own order, Vibrionales. Inhabitants of fresh or salt water, several species are pathogenic, including the type species Vibrio cholerae, which is the agent responsible for cholera. Most bioluminescent bacteria belong to this family, and are typically found as symbionts of deep-sea animals.
Vibrio parahaemolyticus (V. parahaemolyticus) is a curved, rod-shaped, Gram-negative bacterial species found in the sea and in estuaries which, when ingested, may cause gastrointestinal illness in humans. V. parahaemolyticus is oxidase positive, facultatively aerobic, and does not form spores. Like other members of the genus Vibrio, this species is motile, with a single, polar flagellum.
Vibriosis or vibrio infection is an infection caused by bacteria of the genus Vibrio. About a dozen species can cause vibriosis in humans, with the most common in multiple countries across the Northern Hemisphere being Vibrio parahaemolyticus, Vibrio vulnificus, and Vibrio alginolyticus. Vibrio cholerae, can also commonly cause vibriosis, though only those strains that do not produce cholera-specific toxins: non-O 1 or non-O 139. Bacteria that produce these toxins are classified by the World Health Organization as causing cholera, which is a more severe disease. Vibriosis is also an animal disease, and can cause harm to wild and farmed fish among others.
The discovery of disease-causing pathogens is an important activity in the field of medical science. Many viruses, bacteria, protozoa, fungi, helminths, and prions are identified as a confirmed or potential pathogen. In the United States, a Centers for Disease Control and Prevention program, begun in 1995, identified over a hundred patients with life-threatening illnesses that were considered to be of an infectious cause but that could not be linked to a known pathogen. The association of pathogens with disease can be a complex and controversial process, in some cases requiring decades or even centuries to achieve.
Bacterial cellular morphologies are the shapes that are characteristic of various types of bacteria and often key to their identification. Their direct examination under a light microscope enables the classification of these bacteria.
Thiosulfate–citrate–bile salts–sucrose agar, or TCBS agar, is a type of selective agar culture plate that is used in microbiology laboratories to isolate Vibrio species. TCBS agar is highly selective for the isolation of V. cholerae and V. parahaemolyticus as well as other Vibrio species. Apart from TCBS agar, other rapid testing dipsticks like immunochromatographic dipstick is also used in endemic areas such as Asia, Africa and Latin America. Though, TCBS agar study is required for confirmation. This becomes immensely important in cases of gastroenteritis caused by campylobacter species, whose symptoms mimic that of cholera. Since no yellow bacterial growth is observed in case of campylobacter species on TCBS agar, chances of incorrect diagnosis can be rectified. TCBS agar contains high concentrations of sodium thiosulfate and sodium citrate to inhibit the growth of Enterobacteriaceae. Inhibition of gram-positive bacteria is achieved by the incorporation of ox gall, which is a naturally occurring substance containing a mixture of bile salts and sodium cholate, a pure bile salt. Sodium thiosulfate also serves as a sulfur source and its presence, in combination with ferric citrate, allows for the easy detection of hydrogen sulfide production. Saccharose (sucrose) is included as a fermentable carbohydrate for metabolism by Vibrio species. The alkaline pH of the medium enhances the recovery of V. cholerae and inhibits the growth of others. Thymol blue and bromothymol blue are included as indicators of pH changes.
Viable but nonculturable (VBNC) bacteria refers as to bacteria that are in a state of very low metabolic activity and do not divide, but are alive and have the ability to become culturable once resuscitated.
Vibrio anguillarum is a species of prokaryote that belongs to the family Vibrionaceae, genus Vibrio. V. anguillarum is typically 0.5 - 1 μm in diameter and 1 - 3 μm in length. It is a gram-negative, comma-shaped rod bacterium that is commonly found in seawater and brackish waters. It is polarly flagellated, non-spore-forming, halophilic, and facultatively anaerobic. V. anguillarum has the ability to form biofilms. V. anguillarum is pathogenic to various fish species, crustaceans, and mollusks.
Vibrio coralliilyticus is a Gram-negative, rod-shaped bacterium. It has a polar flagellum that is used for motility and has been shown to be critical for its virulence to corals. It is a versatile pathogen, impacting several marine invertebrates including Pocillopora damicornis corals, both the Pacific and Eastern Oyster's larvae and some vertebrates such as the rainbow trout. It is a bacterium of considerable interest given its direct contribution to temperature dependent coral bleaching as well as its impacts on aquaculture where it can contribute to significant mortalities in larval oyster hatcheries. There are several known virulent strains, which appear on both the Pacific and Atlantic Coasts of the United States. After its initial discovery some strains were incorrectly classified as Vibrio tubiashii including the RE22 and RE98 strains but were later reclassified as Vibrio coralliilyticus.
Vibrio tubiashii is a Gram-negative, rod-shaped (0.5 um-1.5 um) marine bacterium that uses a single polar flagellum for motility. It has been implicated in several diseases of marine organisms.
Melanie Blokesch is a German microbiologist. Her research focuses on Vibrio cholerae, the bacterium causing cholera. She is a professor of life sciences at École Polytechnique Fédérale de Lausanne (EPFL), where she heads the Laboratory of Molecular Microbiology.
Virginia L. Miller is a microbiologist known for her work on studying the factors leading to disease caused by bacteria. Miller is an elected fellow of the American Academy of Microbiology (2003) and a former Pew Charitable Trust Biomedical Scholar (1989).