Helicobacter | |
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Scanning electron micrograph of Helicobacter bilis bacteria | |
Scientific classification | |
Domain: | Bacteria |
Phylum: | Campylobacterota |
Class: | "Campylobacteria" |
Order: | Campylobacterales |
Family: | Helicobacteraceae |
Genus: | Helicobacter Goodwin et al. 1989 [1] |
Type species | |
Helicobacter pylori (Marshall et al. 1985) Goodwin et al. 1989 | |
Species | |
See text | |
Synonyms | |
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Helicobacter is a genus of gram-negative bacteria possessing a characteristic helical shape. They were initially considered to be members of the genus Campylobacter , but in 1989, Goodwin et al. published sufficient reasons to justify the new genus name Helicobacter. [2] The genus Helicobacter contains about 35 species. [3] [4] [5]
Some species have been found living in the lining of the upper gastrointestinal tract, as well as the liver of mammals and some birds. [6] The most widely known species of the genus is H. pylori , which infects up to 50% of the human population. [5] It also serves as the type species of the genus. Some strains of this bacterium are pathogenic to humans, as they are strongly associated with peptic ulcers, chronic gastritis, duodenitis, and stomach cancer.
Helicobacter species are able to thrive in the very acidic mammalian stomach by producing large quantities of the enzyme urease, which locally raises the pH from about 2 to a more biocompatible range of 6 to 7. [7] Bacteria belonging to this genus are usually susceptible to antibiotics such as penicillin, are microaerophilic (optimal oxygen concentration between 5 and 14%) capnophiles, and are fast-moving with their flagella. [8] [9]
Comparative genomic analysis has led to the identification of 11 proteins that are uniquely found in the Helicobacteraceae. Of these proteins, seven are found in all species of the family, while the remaining four are not found in any Helicobacter strains and are unique to Wollinella. Additionally, a rare genetic event has led to the fusion of the rpoB and rpoC genes in this family, which is characteristic of them. [10]
Recently, new gastric (H. suis and H. baculiformis) and enterohepatic (H. equorum) species have been reported. H. pylori is of primary importance for medicine, but non-H. pylori species, which naturally inhabit mammals (except humans) and birds, have been detected in human clinical specimens. These encompass two (gastric and enterohepatic) groups, showing different organ specificity. Importantly, some species, such as H. hepaticus, H. mustelae, and probably H. bilis, exhibit carcinogenic potential in animals. They harbour many virulence genes and may cause diseases not only in animals, but also in humans. Gastric species such as H. suis (most often), H. felis, H. bizzozeronii, and H. salomonis have been associated with chronic gastritis and peptic ulcers in humans, and importantly, with higher risk for MALT lymphoma compared to H. pylori.
Enterohepatic species e.g., H. hepaticus,H. bilis, and H. ganmani, have been detected by PCR, but still are not isolated from specimens of patients with hepatobiliary diseases. Moreover, they may be associated with Crohn's disease and ulcerative colitis. The significance of avian helicobacters (H. pullorum, H. anseris, and H. brantae) also has been evaluated extensively. H. cinaedi and H. canis can cause severe infections, mostly in immunocompromised patients with animal exposure. Briefly, the role of these species in veterinary and human medicine is increasingly recognised. Several other topics such as isolation of still uncultured species, antibiotic resistance, and treatment regimens for infections and pathogenesis and possible carcinogenesis in humans should be evaluated. [3]
Helicobacter heilmannii sensu lato (i.e. H. heilmanni s.l.) is a grouping of non-H. pyloriHelicobacter species that take as part of their definition a similarity to H. pylori in being associated with the development of stomach inflammation, stomach ulcers, [11] duodenum ulcers, [12] stomach cancers that are not lymphomas, and extranodal marginal B cell lymphoma of the stomach in humans and animals. [11] Most clinical studies have not identified the exact species of H. heilmanii associated with these diseases, so designated these species as H. heilmanni s.l. However, investigative studies have identified these species in some patients with the cited H. heilmanni s.l.-associated upper gastrointestinal tract diseases. The H. heilmani species identified to date in the stomachs of humans with the cited upper gastrointestinal tract diseases are: Helicobacter bizzozeronii, Helicobacter felis, Helicobacter salomonis, Helicobacter suis , and Helicobacter heilmannii s.s. [11] It is important to recognize the association of H. heilmannii sensu lato with these upper gastrointestinal tract diseases, particularly extranodal marginal zone lymphoma of the stomach, because some of them have been successfully treated using antibiotic-based drug regimens directed against the instigating H. heilmannii sensu lato species. [13] The H. heilmanni s.l.-associated human diseases appear to be acquired from pets and farm animals, so are considered to be zoonotic diseases. [11]
The currently accepted taxonomy is based on the List of Prokaryotic names with Standing in Nomenclature (LPSN) [1] and National Center for Biotechnology Information (NCBI) [14]
16S rRNA based LTP_08_2023 [15] [16] [17] | 120 single copy marker proteins based GTDB 08-RS214 [18] [19] [20] | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Species incertae sedis:
Campylobacter is a type of bacteria that can cause a diarrhea 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.
Peptic ulcer disease is a break in the inner lining of the stomach, the first part of the small intestine, or sometimes the lower esophagus. An ulcer in the stomach is called a gastric ulcer, while one in the first part of the intestines is a duodenal ulcer. The most common symptoms of a duodenal ulcer are waking at night with upper abdominal pain, and upper abdominal pain that improves with eating. With a gastric ulcer, the pain may worsen with eating. The pain is often described as a burning or dull ache. Other symptoms include belching, vomiting, weight loss, or poor appetite. About a third of older people with peptic ulcers have no symptoms. Complications may include bleeding, perforation, and blockage of the stomach. Bleeding occurs in as many as 15% of cases.
Helicobacter pylori, previously known as Campylobacter pylori, is a gram-negative, flagellated, helical bacterium. Mutants can have a rod or curved rod shape, and these are less effective. Its helical body is thought to have evolved in order to penetrate the mucous lining of the stomach, helped by its flagella, and thereby establish infection. The bacterium was first identified as the causal agent of gastric ulcers in 1983 by the Australian doctors Barry Marshall and Robin Warren.
Stomach cancer, also known as gastric cancer, is a cancer that develops from the lining of the stomach. Most cases of stomach cancers are gastric carcinomas, which can be divided into a number of subtypes, including gastric adenocarcinomas. Lymphomas and mesenchymal tumors may also develop in the stomach. Early symptoms may include heartburn, upper abdominal pain, nausea, and loss of appetite. Later signs and symptoms may include weight loss, yellowing of the skin and whites of the eyes, vomiting, difficulty swallowing, and blood in the stool, among others. The cancer may spread from the stomach to other parts of the body, particularly the liver, lungs, bones, lining of the abdomen, and lymph nodes.
Gastritis is inflammation of the lining of the stomach. It may occur as a short episode or may be of a long duration. There may be no symptoms but, when symptoms are present, the most common is upper abdominal pain. Other possible symptoms include nausea and vomiting, bloating, loss of appetite and heartburn. Complications may include stomach bleeding, stomach ulcers, and stomach tumors. When due to autoimmune problems, low red blood cells due to not enough vitamin B12 may occur, a condition known as pernicious anemia.
A microaerophile is a microorganism that requires environments containing lower levels of dioxygen than that are present in the atmosphere (i.e. < 21% O2; typically 2–10% O2) for optimal growth. A more restrictive interpretation requires the microorganism to be obligate in this requirement. Many microaerophiles are also capnophiles, requiring an elevated concentration of carbon dioxide (e.g. 10% CO2 in the case of Campylobacter species).
MALT lymphoma is a form of lymphoma involving the mucosa-associated lymphoid tissue (MALT), frequently of the stomach, but virtually any mucosal site can be affected. It is a cancer originating from B cells in the marginal zone of the MALT.
Rapid urease test, also known as the CLO test, is a rapid diagnostic test for diagnosis of Helicobacter pylori. The basis of the test is the ability of H. pylori to secrete the urease enzyme, which catalyzes the conversion of urea to ammonia and carbon dioxide.
Primary gastric lymphoma is an uncommon condition, accounting for less than 15% of gastric malignancies and about 2% of all lymphomas. However, the stomach is a very common extranodal site for lymphomas. It is also the most common source of lymphomas in the gastrointestinal tract.
Borrelia is a genus of bacteria of the spirochete phylum. Several species cause Lyme disease, also called Lyme borreliosis, a zoonotic, vector-borne disease transmitted by ticks. Other species of Borrelia cause relapsing fever, and are transmitted by ticks or lice, depending on the species of bacteria. A few Borrelia species as Candidatus Borrelia mahuryensis harbor intermediate genetic features between Lyme disease and relapsing fever Borrelia. The genus is named after French biologist Amédée Borrel (1867–1936), who first documented the distinction between a species of Borrelia, B. anserina, and the other known type of spirochete at the time, Treponema pallidum. This bacterium must be viewed using dark-field microscopy, which make the cells appear white against a dark background. Borrelia species are grown in Barbour-Stoenner-Kelly medium. Of 52 known species of Borrelia, 20 are members of the Lyme disease group, 29 belong to the relapsing fever group, and two are members of a genetically distinct third group typically found in reptiles. A proposal has been made to split the Lyme disease group based on genetic diversity and move them to their own genus, Borelliella, but this change is not widely accepted. This bacterium uses hard and soft ticks and lice as vectors. Testing for the presence of the bacteria in a human includes two-tiered serological testing, including immunoassays and immunoblotting.
This is a timeline of the events relating to the discovery that peptic ulcer disease and some cancers are caused by H. pylori. In 2005, Barry Marshall and Robin Warren were awarded the Nobel Prize in Physiology or Medicine for their discovery that peptic ulcer disease (PUD) was primarily caused by Helicobacter pylori, a bacterium with affinity for acidic environments, such as the stomach. As a result, PUD that is associated with H. pylori is currently treated with antibiotics used to eradicate the infection. For decades prior to their discovery, it was widely believed that PUD was caused by excess acid in the stomach. During this time, acid control was the primary method of treatment for PUD, to only partial success. Among other effects, it is now known that acid suppression alters the stomach milieu to make it less amenable to H. pylori infection.
The Synergistota is a phylum of anaerobic bacteria that show Gram-negative staining and have rod/vibrioid cell shape. Although Synergistota have a diderm cell envelope, the genes for various proteins involved in lipopolysaccharides biosynthesis have not yet been detected in Synergistota, indicating that they may have an atypical outer cell envelope. The Synergistota inhabit a majority of anaerobic environments including animal gastrointestinal tracts, soil, oil wells, and wastewater treatment plants and they are also present in sites of human diseases such as cysts, abscesses, and areas of periodontal disease. Due to their presence at illness related sites, the Synergistota are suggested to be opportunistic pathogens but they can also be found in healthy individuals in the microbiome of the umbilicus and in normal vaginal flora. Species within this phylum have also been implicated in periodontal disease, gastrointestinal infections and soft tissue infections. Other species from this phylum have been identified as significant contributors in the degradation of sludge for production of biogas in anaerobic digesters and are potential candidates for use in renewable energy production through their production of hydrogen gas. All of the known Synergistota species and genera are presently part of a single class (Synergistia), order (Synergistiales), and family (Synergistaceae).
Marginal zone lymphomas, also known as marginal zone B-cell lymphomas (MZLs), are a heterogeneous group of lymphomas that derive from the malignant transformation of marginal zone B-cells. Marginal zone B cells are innate lymphoid cells that normally function by rapidly mounting IgM antibody immune responses to antigens such as those presented by infectious agents and damaged tissues. They are lymphocytes of the B-cell line that originate and mature in secondary lymphoid follicles and then move to the marginal zones of mucosa-associated lymphoid tissue (MALT), the spleen, or lymph nodes. Mucosa-associated lymphoid tissue is a diffuse system of small concentrations of lymphoid tissue found in various submucosal membrane sites of the body such as the gastrointestinal tract, mouth, nasal cavity, pharynx, thyroid gland, breast, lung, salivary glands, eye, skin and the human spleen.
Helicobacter cinaedi is a bacterium in the family Helicobacteraceae, Campylobacterales order, Helicobacteraceae family, Helicobacter genus. It was formerly known as Campylobacter cinaedi until molecular analysis published in 1991 led to a major revision of the genus Campylobacter. H. cinaedi is a curved, spiral, or fusiform rod with flagellum at both of its ends which it uses to dart around. The bacterium is a pathogen.
Helicobacter felis is a bacterial species in the Helicobacteraceae family, Campylobacterales order, Helicobacter genus. This bacterium is Gram-negative, microaerophilic, urease-positive, and spiral-shaped. Its type strain is CS1T. It can be pathogenic.
Helicobacter salomonis is a species within the Helicobacter genus of Gram-negative bacteria. Helicobacter pylori is by far the best known Helicobacter species primarily because humans infected with it may develop gastrointestinal tract diseases such as stomach inflammation, stomach ulcers, duodenal ulcers, stomach cancers of the nonlymphoma type, and various subtypes of extranodal marginal zone lymphomass, e.g. those of the stomach, small intestines, large intestines, and rectumn. H. pylori is also associated with the development of bile duct cancer and has been associated with a wide range of other diseases, although its role in the development of many of these other diseases requires further study. Humans infected with H. salomonis may develop some of the same gastrointestinal diseases viz., stomach inflammation, stomach ulcers, duodenal ulcers, stomach cancers that are not lymphomas, and extranodal marginal B cell lymphomas of the stomach. Other non-H. pylori Helicobacter species that are known to be associated with these gastrointestinal diseases are Helicobacter bizzozeronii, Helicobacter suis, Helicobacter felis, and Helicobacter heilmannii s.s. Because of their disease associations, these four Helicobacter species plus H. salomonis are often group together and termed Helicobacter heilmannii sensu lato.
Helicobacter heilmannii sensu lato refers to a group of bacterial species within the Helicobacter genus. The Helicobacter genus consists of at least 40 species of spiral-shaped flagellated, Gram-negative bacteria of which the by far most prominent and well-known species is Helicobacter pylori. H. pylori is associated with the development of gastrointestinal tract diseases such as stomach inflammation, stomach ulcers, duodenal ulcers, stomach cancers that are not lymphomas, and various subtypes of extranodal marginal zone lymphomas, e.g. those of the stomach, small intestines, large intestines, and rectumn. H. pylori has also been associated with the development of bile duct cancer and has been associated with a wide range of other diseases although its role in the development of many of these other diseases requires further study.
Helicobacter bizzozeronii is a species within the Helicobacter genus of Gram-negative bacteria. Helicobacter pylori is by far the best known Helicobacter species, primarily because humans infected with it may develop gastrointestinal tract diseases such as stomach inflammation, stomach ulcers, duodenal ulcers, stomach cancers of the nonlymphoma type, and various subtypes of extranodal marginal zone lymphomass, e.g. those of the stomach, small intestines, large intestines, and rectumn. H. pylori is also associated with the development of bile duct cancer and has been associated with a wide range of other diseases although its role in the development of many of these other diseases requires further study. Humans infected with H. bizzozeronii are prone to develop some of the same gastrointestinal diseases viz., stomach inflammation, stomach ulcers, duodenal ulcers, stomach cancers that are not lymphomas, and extranodal marginal B cell lymphomas of the stomach. Other non-H. pylori Helicobacter species that are known to be associated with these gastrointestinal diseases are Helicobacter felis, Helicobacter salomonis, Helicobacter suis, and Helicobacter heilmannii s.s. Because of their disease associations, these four Helicobacter species plus H. bizzozeronii are often grouped together and termed Helicobacter heilmannii sensu lato.
Helicobacter suis is a species within the Helicobacter genus of Gram-negative bacteria. Helicobacter pylori is by far the best known Helicobacter species, primarily because humans infected with it may develop gastrointestinal tract diseases such as stomach inflammation, stomach ulcers, duodenal ulcers, stomach cancers of the nonlymphoma type, and various subtypes of extranodal marginal zone lymphomass, e.g. those of the stomach, small intestines, large intestines, and rectumn. H. pylori is also associated with the development of bile duct cancer and has been associated with a wide range of other diseases although its role in the development of many of these other diseases requires further study. Humans infected with H. suis may develop some of the same gastrointestinal diseases - stomach inflammation, stomach ulcers, duodenal ulcers, stomach cancers that are not lymphomas, and extranodal marginal B cell lymphomas of the stomach. Other non-H. pylori Helicobacter species that are known to be associated with these gastrointestinal diseases are Helicobacter bizzozeronii, Helicobacter salomonis, Helicobacter felis, and Helicobacter heilmannii s.s. Because of their disease associations, these four Helicobacter species plus H. suis are often group together and termed Helicobacter heilmannii sensu lato.
Helicobacter heilmannii s.s. is a species within the Helicobacter genus of Gram negative bacteria. Helicobacter pylori is by far the best known Helicobacter species primarily because humans infected with it may develop gastrointestinal tract diseases such as stomach inflammation, stomach ulcers, duodenal ulcers, stomach cancers of the non-lymphoma type, and various subtypes of extranodal marginal zone lymphomass, e.g. those of the stomach, small intestines, large intestines, and rectumn. H. pylori is also associated with the development of bile duct cancer and has been associated with a wide range of other diseases although its role in the development of many of these other diseases requires further study. Humans infected with H. heilmannii s.s. may develop some of the same gastrointestinal diseases viz., stomach inflammation, stomach ulcers, duodenal ulcers, stomach cancers that are not lymphomas, and extranodal marginal B cell lymphomas of the stomach. Other non-H. pylori Helicobacter species that are known to be associated with these gastrointestinal diseases are Helicobacter bizzozeronii, Helicobacter suis, Helicobacter felis, and Helicobacter salomonis. Because of their disease associations, these four Helicobacter species plus H. heilmannii s.s. are often group together and termed Helicobacter heilmannii sensu lato.