Helicobacter

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iHelicobacter

Scanning electron micrograph of Helicobacter sp. bacteria.

Scientific classification

Kingdom:	Bacteria
Phylum:	Proteobacteria
Class:	Epsilon Proteobacteria
Order:	Campylobacterales
Family:	Helicobacteraceae
Genus:	Helicobacter Goodwin et al. 1989

Species

H. acinonychis
H. aurati
H. bilis
H. bizzozeronii
H. canadensis
H. canis
H. cholecystus
H. cinaedi
H. felis
H. fennelliae
H. ganmani
H. hepaticus
H. mesocricetorum
H. muridarum
H. mustelae
H. pametensis
H. pullorum
H. pylori
H. rodentium
H. salomonis
H. trogontum
H. typhlonius

Helicobacter is a genus of Gram-negative bacteria that have a characteristic spiral shape and have been found in the lining of the stomach and upper gastrointestinal tract, as well as the liver of mammals and some birds<ref>Ryan KJ; Ray CG (editors) (2004). Sherris Medical Microbiology, 4th ed., McGraw Hill. ISBN 0-8385-8529-9.</ref>. The best known species of this genus is H. pylori which is a human pathogen and is responsible for most cases of peptic ulcer and chronic gastritis; it also serves as the type species of the genus.

Helicobacter sp. are able to thrive in the strongly acidic mammalian stomach by producing large quantities of a urease, which locally raises the pH from ~2 to a more hospitable range (pH 6-7)<ref>Dunn BE; Cohen H; Blaser MJ. (1997). "Helicobacter pylori.". Clin Microbiol Rev. 10: 720–741.</ref>. Bacteria belonging to this genus are susceptible to antibiotics such as penicillin, are microaerophilic (require small amounts of oxygen), and are fast-moving with multiple flagella<ref>Hua JS; Zheng PY; Ho B (1999). "Species differentiation and identification in the genus of Helicobacter.". World Journal of Gastroenterology. 5 (1): 7–9.</ref>.

Initially, these bacteria were considered to be members of the genus Campylobacter, but since 1989 they are grouped in their own genus <ref>Goodwin CS; Armstrong JA; Chilvers T; Peters M; Collins MD; Sly L; McConnell W; Harper WES. (1989). "Transfer of Campylobacter pylori and Campylobacter mustelae to Helicobacter gen. nov. as Helicobacter pylori comb. nov. and Helicobacter mustelae comb. nov., respectively.". Int. J. Syst. Bacteriol. 39: 397–405.</ref>^,<ref>Vandamme P; Falsen E; Rossaq R; Hoste B; Seagers P; Tytgat R; De Lay J. (1991). "Revision of Campylobacter, Helicobacter, and Wolinella taxonomy: emendation of generic descriptions and proposal of Arcobacter gen. nov.". Int. J. Syst. Bacteriol. 41: 88–103.</ref>.