''Helicobacter heilmannii sensu lato'' refers to a group of

bacteria Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were among ...

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

within the ''

Helicobacter ''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 justif ...

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

. The ''Helicobacter'' genus consists of at least 40 species of spiral-shaped (also described as corkscrew-shaped)

flagellated A flagellum (; ) is a hairlike appendage that protrudes from certain plant and animal sperm cells, and from a wide range of microorganisms to provide motility. Many protists with flagella are termed as flagellates. A microorganism may have fro ...

Gram-negative Gram-negative bacteria are bacteria that do not retain the crystal violet stain used in the Gram staining method of bacterial differentiation. They are characterized by their cell envelopes, which are composed of a thin peptidoglycan cell wall ...

bacteria of which the by far most prominent and well-known species is ''

Helicobacter pylori ''Helicobacter pylori'', previously known as ''Campylobacter pylori'', is a gram-negative, microaerophilic, spiral (helical) bacterium usually found in the stomach. Its helical shape (from which the genus name, helicobacter, derives) is though ...

'' (''H. pylori''). ''H. pylori'' is associated with the development of

gastrointestinal tract The gastrointestinal tract (GI tract, digestive tract, alimentary canal) is the tract or passageway of the digestive system that leads from the mouth to the anus. The GI tract contains all the major organ (biology), organs of the digestive syste ...

diseases such as stomach inflammation,

stomach ulcers Peptic ulcer disease (PUD) 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 ...

duodenal ulcers Peptic ulcer disease (PUD) 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 ...

stomach cancer 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. Lymph ...

s that are not

lymphomas Lymphoma is a group of blood and lymph tumors that develop from lymphocytes (a type of white blood cell). In current usage the name usually refers to just the cancerous versions rather than all such tumours. Signs and symptoms may include enlar ...

, and various subtypes of extranodal marginal zone lymphomass, e.g. those of the

stomach The stomach is a muscular, hollow organ in the gastrointestinal tract of humans and many other animals, including several invertebrates. The stomach has a dilated structure and functions as a vital organ in the digestive system. The stomach i ...

small intestines The small intestine or small bowel is an organ in the gastrointestinal tract where most of the absorption of nutrients from food takes place. It lies between the stomach and large intestine, and receives bile and pancreatic juice through the pa ...

large intestines The large intestine, also known as the large bowel, is the last part of the gastrointestinal tract and of the digestive system in tetrapods. Water is absorbed here and the remaining waste material is stored in the rectum as feces before being rem ...

, and rectumn. ''H. pylori'' has also been associated with the development of

bile duct cancer Cholangiocarcinoma, also known as bile duct cancer, is a type of cancer that forms in the bile ducts. Symptoms of cholangiocarcinoma may include abdominal pain, yellowish skin, weight loss, generalized itching, and fever. Light colored stool ...

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. The ''H. heilmannii sensu lato'' species of bacteria take as part of their definition a similarity to ''H. pylori'' in being associated with the development of stomach inflammation, stomach ulcers, duodenal ulcers, stomach cancers that are not lymphomas, and extranodal marginal B cell lymphomas of the stomach. It is important to recognize and diagnose the association of ''H. heilmannii sensu lato'' with these upper gastrointestinal tract diseases, particularly extranodal marginal zone lymphoma of the stomach, because many of them have been successfully treated using antibiotic-based drug regimens directed against the instigating ''H. heilmannii sensu lato'' bacterial species.

Taxonomy

The current taxonomy of ''Helicobacter'' bacteria is a bit complex and incomplete, with new species currently being considered as possibly belonging to this genus. Within the ''Helicobacter'' genus, ''H. heilmannii s. l.'' is a group of ''Helicobacter'' species that are distinguished from ''H. pylori'' by being two- to three-fold larger in size (they are 4-10

micrometers The micrometre (American and British English spelling differences#-re, -er, international spelling as used by the International Bureau of Weights and Measures; SI symbol: μm) or micrometer (American and British English spelling differences# ...

in length and 0.5-0.8 micrometers in width, while ''H. pylori'' is 2.5-4.0 micrometers in length and 0.5-1.0 micrometers in width) as well as in the position and number of their

flagella A flagellum (; ) is a hairlike appendage that protrudes from certain plant and animal sperm cells, and from a wide range of microorganisms to provide motility. Many protists with flagella are termed as flagellates. A microorganism may have f ...

(they have 4-23 flagella that are located at only one of their ends, while ''H. pylori'' has 4-8 flagella divided between both of their ends). The ''Helicobacter heilmannii'' grouping of bacteria is further divided into two groups: ''H. heilmannii sensu stricto'' (''H. heilmannii s.s.'') and ''H. heilmannii sensu lato'' (''H. heilmannii s.l.''). ''H. heilmannii s.l.'' is ''Helicobacter heilmannii'' bacterial species that have been isolated from the stomachs of humans and animals, but identified only on the basis of their

histopathological Histopathology (compound of three Greek words: ''histos'' "tissue", πάθος ''pathos'' "suffering", and -λογία ''-logia'' "study of") refers to the microscopic examination of tissue in order to study the manifestations of disease. Spec ...

appearance, electron microscopic appearance, and/or other crude taxonomic data: in most studies, the species of these ''H. heilmannii'' bacteria is not defined other than that they are non-''H. pylori'' isolated from the stomachs of humans and animals. ''H. heilmanni s.l.'' is a clinically useful designation indicating unidentified ''H. pylori'' species of ''H. heilmannii'' that, like ''H. pylori'', can cause upper gastrointestinal tract diseases in humans, and are sensitive to a common set of antibiotic regimens. ''H. heilmanni s.s.'', in contrast, is ''Helicobacter heilmannii'' isolates whose species have been clearly defined, typically by unambiguous

molecular biology Molecular biology is the branch of biology that seeks to understand the molecular basis of biological activity in and between cells, including biomolecular synthesis, modification, mechanisms, and interactions. The study of chemical and physi ...

methods.

Epidemiology and transmission to humans

Most clinical studies have not identified the exact species of ''H. heilmannii'' associated with upper gastrointestinal tract disease and therefore designated these bacterial species as ''H. heilmanni s.l.'' However, investigative studies have identified these species in some patients with ''H. heilmanni s.l.''-associated stomach diseases. The ''H. heilmanni s.s.'' species identified to date in the stomachs of humans with these upper gastrointestinal tract diseases, the natural hosts for these species, the sites these species colonize in their natural, nonhuman hosts, and each species prevalence as a percentage of all ''H. heilmannii s.s.'' species isolated from humans are given in the following table. # ''H. heilmannii s.s.'' is a species in the ''H. heilmannii'' group; the appended "s.s." abbreviation is used to indicate that it refers to a specific species rather than the group. Many reports suggest that individuals, including children, acquire ''H. heilmanni s.l.'' infections by close contact with cats, dogs, pigs, and other farm animals, as well as by eating raw pork contaminated by ''H. suis''. The ''H. heilmanni s.s.'' species listed in the above table have been isolated from these animals, while ''H. suis'' has been isolated from fresh raw pork (''H. suis'' remains viable up to 72 hours in fresh raw pork). Furthermore, a higher rate of ''H. heilmanni s.l.''-associated infections occurs in rural areas. These findings suggest that the ''H. heilmanni s.l.''-associated diseases are

zoonotic diseases A zoonosis (; plural zoonoses) or zoonotic disease is an infectious disease of humans caused by a pathogen (an infectious agent, such as a bacterium, virus, parasite or prion) that has jumped from a non-human (usually a vertebrate) to a human. ...

, i.e.,

infectious diseases An infection is the invasion of tissues by pathogens, their multiplication, and the reaction of host tissues to the infectious agent and the toxins they produce. An infectious disease, also known as a transmissible disease or communicable dise ...

that are caused by

pathogen In biology, a pathogen ( el, πάθος, "suffering", "passion" and , "producer of") in the oldest and broadest sense, is any organism or agent that can produce disease. A pathogen may also be referred to as an infectious agent, or simply a germ ...

that spread from animals to humans.

''H. heilmanni s.l.''-associated diseases

''H. heilmanni s.l.'' has been detected in the stomach of patients with acute and chronic

gastritis 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 (see dyspepsia). Other possi ...

, peptic ulcer disease of the stomach and duodenum, nonlymphoma types of stomach cancers, and extranodal marginal zone B-cell lymphoma of the stomach. Based on the ability of antibiotic-based drug regimens to improve and cure some of these diseases in humans and animal models, ''H. heilmanni s.l.'' infections are considered to be key contributors in their development and/or progression. ''H. pylori'' is far more often involved in these diseases: ''H. heilmanni s.l.'' is typically associated with <1% of all ''Helicobacter''-induced upper gastrointestinal tract diseases, while ''H. pylori'' is associated with the remaining cases. In certain Asian countries, however, ''H. heilmanni s.l.'' appears to be associated with higher percentages of upper gastrointestinal tract diseases; for example, it is associated with 4% and 6.2%, respectively, of all ''Helicobacter''-associated diseases in China and Thailand.

Treatment of ''H. heilmanni s.l.''- associated diseases

The treatment of patients with ''H. heilmanni s.l.''-associated diseases has employed the same antibiotic-based drug regiments that have been successfully used to treat and cure ''H. pylori''-associated diseases. These regimens have eradicated the ''H. heilmanni s.l.'' bacterium in the stomach to achieve symptomatic relief and total regression of some of the infection-associated nonmalignant, as well as malignant diseases, particularly extranodal marginal B-cell lymphoma. Drug regimens of

amoxicillin Amoxicillin is an antibiotic medication used to treat a number of bacterial infections. These include middle ear infection, strep throat, pneumonia, skin infections, and urinary tract infections among others. It is taken by mouth, or less c ...

clarithromycin Clarithromycin, sold under the brand name Biaxin among others, is an antibiotic used to treat various bacterial infections. This includes strep throat, pneumonia, skin infections, ''H. pylori'' infection, and Lyme disease, among others. Clarith ...

, plus a

proton pump inhibitor Proton-pump inhibitors (PPIs) are a class of medications that cause a profound and prolonged reduction of stomach acid production. They do so by irreversibly inhibiting the stomach's H+/K+ ATPase proton pump. They are the most potent inhibitors ...

metronidazole Metronidazole, sold under the brand name Flagyl among others, is an antibiotic and antiprotozoal medication. It is used either alone or with other antibiotics to treat pelvic inflammatory disease, endocarditis, and bacterial vaginosis. It is ef ...

, clarithromycin, plus a proton pump inhibitor have been used to treat ''S. heilmannii s.l.-associated upper gastrointestinal tract diseases successfully.

References

{{Taxonbar, from=Q7780536 Gram-negative bacteria Pathogenic bacteria Campylobacterota Infectious causes of cancer Carcinogenesis Lymphoma