Helicobacter
219856
222851684
2008-07-01T12:40:52Z
Jonathan Webley
304806
/* Treatment */ make links
{{Taxobox
| color = lightgrey
| name = ''Helicobacter''
| image = Helicobacter sp 01.jpg
| image_width = 240px
| image_caption = [[Scanning electron microscope|Scanning electron micrograph]] of ''Helicobacter'' bacteria.
| regnum = [[Bacterium|Bacteria]]
| phylum = [[Proteobacteria]]
| classis = [[Epsilon Proteobacteria]]
| ordo = [[Campylobacterales]]
| familia = '''Helicobacteraceae'''
| genus = '''''Helicobacter'''''
| genus_authority = Goodwin ''et al.'' 1989
| subdivision_ranks = Species
| subdivision =
''[[Helicobacter acinonychis|H. acinonychis]]''<br>
''[[Helicobacter anseris|H. anseris]]''<br>
''[[Helicobacter aurati|H. aurati]]''<br>
''[[Helicobacter bilis|H. bilis]]''<br>
''[[Helicobacter bizzozeronii|H. bizzozeronii]]''<br>
''[[Helicobacter brantae|H. brantae]]''<br>
''[[Helicobacter canadensis|H. canadensis]]''<br>
''[[Helicobacter canis|H. canis]]''<br>
''[[Helicobacter cholecystus|H. cholecystus]]''<br>
''[[Helicobacter cinaedi|H. cinaedi]]''<br>
''[[Helicobacter cynogastricus|H. cynogastricus]]''<br>
''[[Helicobacter felis|H. felis]]''<br>
''[[Helicobacter fennelliae|H. fennelliae]]''<br>
''[[Helicobacter ganmani|H. ganmani]]''<br>
''[[Helicobacter hepaticus|H. hepaticus]]''<br>
''[[Helicobacter mesocricetorum|H. mesocricetorum]]''<br>
''[[Helicobacter marmotae|H. marmotae]]''<br>
''[[Helicobacter muridarum|H. muridarum]]''<br>
''[[Helicobacter mustelae|H. mustelae]]''<br>
''[[Helicobacter pametensis|H. pametensis]]''<br>
''[[Helicobacter pullorum|H. pullorum]]''<br>
''[[Helicobacter pylori|H. pylori]]''<br>
''[[Helicobacter rappini|H. rappini]]''<br>
''[[Helicobacter rodentium|H. rodentium]]''<br>
''[[Helicobacter salomonis|H. salomonis]]''<br>
''[[Helicobacter trogontum|H. trogontum]]''<br>
''[[Helicobacter typhlonius|H. typhlonius]]''<br>
''[[Helicobacter winghamensis|H. winghamensis]]''
}}
'''''Helicobacter''''' is a [[genus]] of [[Gram-negative]] [[bacterium|bacteria]] possessing a characteristic [[helix]] shape. They were initially considered to be members of the ''[[Campylobacter]]'' genus, but since [[1989]] they have been grouped in their own genus.<ref>{{cite journal | author = Goodwin CS, Armstrong JA, Chilvers T, ''et al'' | title = Transfer of ''Campylobacter pylori'' and ''Campylobacter mustelae'' to ''Helicobacter'' gen. nov. as ''Helicobacter pylori'' comb. nov. and ''Helicobacter mustelae'' comb. nov., respectively.| journal = Int. J. Syst. Bacteriol.| year = 1989| volume = 39| issue = | pages = 397–405| url= }}</ref><ref>{{cite journal | author = Vandamme P, Falsen E, Rossaq R, ''et al'' | title = Revision of ''Campylobacter'', ''Helicobacter'', and ''Wolinella'' taxonomy: emendation of generic descriptions and proposal of ''Arcobacter'' gen. nov. | journal = Int. J. Syst. Bacteriol.| year = 1991| volume = 41| issue = | pages = 88–103 | url= http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=1704793&dopt=Citation}}</ref><ref name= YamaokaY>{{cite book | author = Yamaoka Y (editor). | title = Helicobacter pylori: Molecular Genetics and Cellular Biology | publisher = Caister Academic Press | year = 2008 | url=http://www.horizonpress.com/hpl2 | id = [http://www.horizonpress.com/hpl2 ISBN 978-1-904455-31-8 ]}}</ref>
Some [[species (biology)|species]] have been found living in the lining of the upper [[gastrointestinal]] tract, as well as the [[liver]] of [[mammal]]s and some [[bird]]s.<ref>{{cite book | author = Ryan KJ, Ray CG (editors) | title = Sherris Medical Microbiology | edition = 4th ed. | publisher = McGraw Hill | year = 2004 | isbn = 0-8385-8529-9 }}</ref>. The most widely known species of the genus is ''[[Helicobacter pylori|H. pylori]]'' which infects up to 50% of the human population.<ref name= YamaokaY>{{cite book | author = Yamaoka Y (editor). | title = Helicobacter pylori: Molecular Genetics and Cellular Biology | publisher = Caister Academic Press | year = 2008 | url=http://www.horizonpress.com/hpl2 | id = [http://www.horizonpress.com/hpl2 ISBN 978-1-904455-31-8 ]}}</ref> Some strains of this bacterium are [[pathogen]]ic to humans as it is strongly associated with [[peptic ulcer]]s, chronic [[gastritis]], [[duodenitis]], and [[stomach cancer]]. It also serves as the [[type species]] of the genus.
''Helicobacter'' spp. are able to thrive in the very [[acidic]] mammalian [[stomach]] by producing large quantities of the [[enzyme]] [[urease]], which locally raises the [[pH]] from ~2 to a more biocompatible range of 6 to 7.<ref>{{cite journal | author = Dunn BE, Cohen H, Blaser MJ| title = ''Helicobacter pylori''. | journal = Clin Microbiol Rev. | year = 1997 | volume = 10 | issue = | pages = 720–741 | url= http://cmr.asm.org/cgi/reprint/10/4/720?}}</ref> Bacteria belonging to this genus are usually susceptible to [[antibiotics]] such as [[penicillin]], are [[microaerophilic]] (require small amounts of [[oxygen]]), and are fast-moving with their [[flagella]].<ref>{{cite journal | author = Hua JS, Zheng PY, Ho B | title = Species differentiation and identification in the genus of ''Helicobacter''. | journal = World Journal of Gastroenterology. | year = 1999 | volume = 5 | issue = 1 | pages = 7–9 | url=http://www.wjgnet.com/1007-9327/5/7.pdf}}</ref><ref name= Rustetal>{{cite book |chapterurl=http://www.horizonpress.com/hpl2 |author= Rust et al|year=2008|chapter=Helicobacter Flagella, Motility and Chemotaxis | title = Helicobacter pylori: Molecular Genetics and Cellular Biology (Yamaoka Y, ed.)| publisher = Caister Academic Press | year = 2008 | id = [http://www.horizonpress.com/hpl2 ISBN 978-1-904455-31-8 ]}}</ref>
===Helicobacter Facts.<ref>{{cite book | author = Kathleen Park Talaro | title = Foundations in Microbiology | edition = 6th ed. | publisher = McGraw Hill | year = 2006 | isbn = 0072994959 }}</ref>===
Curved cells discovered in 1979 in stomach biopsied specimens.
Causes 90% of stomach & duodenal ulcers.
People with type O blood have a 1.5-2X higher rate of ulcers.
Produces large amounts of urease.
Infection common especially in lower socioeconomic class/developing nations.
Humans primary reservoir.
Person-to-person spread via fecal-oral route.
Ubiquitous, no seasonal incidence.
===Gastric and Lymphoid Cancers===
In 1994, the [[World Health Organization]]’s International Agency for Research on Cancer (IARC) classified H. pylori as a Group 1 carcinogen. This decision was based on the results of numerous studies that confirmed the association between H. pylori infection and gastric adenocarcinoma. H. pylori infection also significantly increases the risk of gastric lymphoma of mucosa-associated lymphoid tissue (MALT) (Suerbaum, 2002).
===Diagnosis===
H. pylori infection can be confirmed by invasive or noninvasive methods. Invasive tests require upper esophagogastroduodenal (EGD) endoscopy, which is considered the reference method of diagnosis. During endoscopy, biopsy specimens of the stomach and duodenum are obtained, and the diagnosis of H. pylori can be made by urease testing, histology and/or culture. If possible, noninvasive testing is done before tissue testing.
H. pylori stool antigen (HpSA) testing is based on monoclonal antibody immunochromatography of stool samples. This testing method identifies active infection and can be used to detect eradication after treatment. A sensitivity and specificity range of 92–98% is reported in the literature for stool antigen testing.
Serological assays (blood serum) measure specific H. pylori immunoglobulin G (IgG) antibodies that can determine if an individual has been infected. The sensitivity and specificity of these assays range from 80–95%, depending on the assay used. Serological testing has been the mainstay of H. pylori diagnosis, particularly in primary care, due to the accessibility, rapid results and low cost of this testing method.
Urease test, Urease Breath Test (UBT) (positive in as little as 2 hours)
<ref>{{cite journal | author = Robert P H Logan, Marjorie M Walker| title = ''Epidemiology and diagnosis of Helicobacter pylori infection ''. | journal = BMJ 2001;323:920-922 ( 20 October ) | year = 2001| volume = 323| issue = | pages = –741 | url= http://www.bmj.com/cgi/content/full/323/7318/920| pmid = 11668141| doi = 10.1136/bmj.323.7318.920}}</ref>
===Treatment===
Therapy is with [[tetracycline]], [[metronidazole]], [[azithromycine]], [[bismuth]] ([[Peptobismol]]).
==References==
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==See also==
*''[[Helicobacter pylori]]''
== External links==
* [http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Tree&id=209&lvl=3&lin=f&keep=1&srchmode=1&unlock List of species in ''Helicobacter'', with links to sequence information]
[[Category:Proteobacteria]]
[[Category:Gastroenterology]]
[[Category:Conditions diagnosed by stool test]]
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