Editing Helicobacter pylori (section)

{{Short description|Species of bacteria}}
{{Featured article}}
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{{Use dmy dates|date=August 2018}}
{{Speciesbox
| image = EMpylori.jpg
| image_caption = [[Electron micrograph]] of ''H. pylori'' possessing multiple [[flagella]] ([[negative staining]])
| genus = Helicobacter
| species = pylori
| authority = (Marshall ''et al.'' 1985) Goodwin ''et al.'', 1989
| synonyms =
* ''Campylobacter pylori'' <small>Marshall ''et al.'' 1985</small>
}}

'''''Helicobacter pylori''''', previously known as '''''Campylobacter pylori''''', is a [[gram-negative]], [[Flagellum#bacterial|flagellated]], [[Bacterial cellular morphologies#Helical|helical bacterium]]. Mutants can have a rod or curved rod shape that exhibits less [[virulence]].<ref name="Martínez">{{cite journal |vauthors=Martínez LE, O'Brien VP, Leverich CK, Knoblaugh SE, Salama NR |title=Nonhelical Helicobacter pylori Mutants Show Altered Gland Colonization and Elicit Less Gastric Pathology than Helical Bacteria during Chronic Infection |journal=Infect Immun |volume=87 |issue=7 |pages= |date=July 2019 |pmid=31061142 |pmc=6589060 |doi=10.1128/IAI.00904-18 |url=}}</ref><ref name="Salama">{{cite journal |vauthors=Salama NR |title=Cell morphology as a virulence determinant: lessons from Helicobacter pylori |journal=Curr Opin Microbiol |volume=54 |issue= |pages=11–17 |date=April 2020 |pmid=32014717 |pmc=7247928 |doi=10.1016/j.mib.2019.12.002 |url=}}</ref> Its [[Helix|helical]] body (from which the [[genus]] name ''[[Helicobacter]]'' derives) is thought to have evolved to penetrate the [[gastric mucosa|mucous lining]] of the [[stomach]], helped by its [[flagella]], and thereby establish infection.<ref name="Yamaoka">{{cite book |isbn=978-1-904455-31-8 |chapter-url=http://www.horizonpress.com/hpl2 |vauthors=Rust M, Schweinitzer T, Josenhans C |year=2008 |chapter=Helicobacter Flagella, Motility and Chemotaxis |title=''Helicobacter pylori'': Molecular Genetics and Cellular Biology |editor=Yamaoka, Y. |publisher=Caister Academic Press |access-date=1 April 2008 |archive-date=18 August 2016 |archive-url=https://web.archive.org/web/20160818123135/http://www.horizonpress.com/hpl2 |url-status=live }}</ref><ref name="Salama" /> While many earlier reports of an association between bacteria and the ulcers had existed, such as the works of [[John Lykoudis]],<ref>{{Cite journal |last=Kidd |first=Mark |last2=Modlin |first2=Irvin M. |date=1998 |title=A Century of Helicobacter pylori |url=https://karger.com/article/doi/10.1159/000007461 |journal=Digestion |language=en |volume=59 |issue=1 |pages=1–15 |doi=10.1159/000007461 |issn=0012-2823}}</ref><ref>{{Cite journal |last=Rigas |first=Basil |last2=Feretis |first2=Chris |last3=Papavassiliou |first3=Efstathios D |date=November 1999 |title=John Lykoudis: an unappreciated discoverer of the cause and treatment of peptic ulcer disease |url=https://linkinghub.elsevier.com/retrieve/pii/S0140673699060341 |journal=The Lancet |language=en |volume=354 |issue=9190 |pages=1634–1635 |doi=10.1016/S0140-6736(99)06034-1}}</ref><ref>{{Cite journal |last=Baird |first=A. Gordon |date=August 2016 |title=Is general practice in the wrong PLACE? |url=https://pmc.ncbi.nlm.nih.gov/articles/PMC4979950/ |journal=The British Journal of General Practice: The Journal of the Royal College of General Practitioners |volume=66 |issue=649 |pages=424 |doi=10.3399/bjgp16X686329 |issn=1478-5242 |pmc=4979950 |pmid=27481970}}</ref><ref>{{Cite book |title=Helicobacter pioneers: firsthand accounts from the scientists who discovered helicobacters, 1892 - 1982 |date=2002 |publisher=Blackwell Science Asia |isbn=978-0-86793-035-1 |editor-last=Marshall |editor-first=Barry J. |edition=1. print |location=Carlton, South Victoria}}</ref> it was only in 1983 when the bacterium was formally described for the first time in the English-language Western literature as the causal agent of [[peptic ulcer|gastric ulcers]] by Australian [[physician-scientist]]s [[Barry Marshall]] and [[Robin Warren]].<ref>{{cite journal | vauthors = Warren JR, Marshall B | title = Unidentified curved bacilli on gastric epithelium in active chronic gastritis | journal = Lancet | volume = 1 | issue = 8336 | pages = 1273–5 | date = June 1983 | pmid = 6134060 | doi = 10.1016/S0140-6736(83)92719-8 | s2cid = 1641856 }}</ref><ref name="FitzGerald">{{cite book |vauthors=FitzGerald R, Smith SM |title=Helicobacter Pylori |chapter=An Overview of Helicobacter pylori Infection |series=Methods Mol Biol |volume=2283 |pages=1–14 |date=2021 |pmid=33765303 |doi=10.1007/978-1-0716-1302-3_1 |isbn=978-1-0716-1301-6 |s2cid=232365068 |chapter-url=}}</ref> In 2005, the pair was awarded the [[Nobel Prize in Physiology or Medicine]] for their discovery.<ref>{{cite journal |vauthors=Watts G |title=Nobel prize is awarded to doctors who discovered H pylori |journal=BMJ |volume=331 |issue=7520 |pages=795 |date=October 2005 |pmid=16210262 |pmc=1246068 |doi=10.1136/bmj.331.7520.795 |url=}}</ref>

Infection of the stomach with ''H. pylori'' does not necessarily cause illness: over half of the global population is infected, but most individuals are asymptomatic.<ref name="cancer.gov2023">{{cite web |title=Helicobacter pylori (H. pylori) and Cancer - NCI |url=https://www.cancer.gov/about-cancer/causes-prevention/risk/infectious-agents/h-pylori-fact-sheet |website=www.cancer.gov |access-date=18 October 2023 |language=en |date=25 September 2013 |archive-date=19 October 2023 |archive-url=https://web.archive.org/web/20231019062643/https://www.cancer.gov/about-cancer/causes-prevention/risk/infectious-agents/h-pylori-fact-sheet |url-status=live }}</ref><ref name="de Brito">{{cite journal |vauthors=de Brito BB, da Silva FA, Soares AS, Pereira VA, Santos ML, Sampaio MM, Neves PH, de Melo FF |title=Pathogenesis and clinical management of Helicobacter pylori gastric infection |journal=World J Gastroenterol |volume=25 |issue=37 |pages=5578–5589 |date=October 2019 |pmid=31602159 |pmc=6785516 |doi=10.3748/wjg.v25.i37.5578 |doi-access=free }}</ref> Persistent [[colonisation (biology)|colonization]] with more virulent strains can induce a number of gastric and non-gastric disorders.<ref name="Chen">{{cite journal |vauthors=Chen CC, Liou JM, Lee YC, Hong TC, El-Omar EM, Wu MS |title=The interplay between Helicobacter pylori and gastrointestinal microbiota |journal=Gut Microbes |volume=13 |issue=1 |pages=1–22 |date=2021 |pmid=33938378 |pmc=8096336 |doi=10.1080/19490976.2021.1909459 |url=}}</ref> Gastric disorders due to infection begin with [[gastritis]], or inflammation of the stomach lining.<ref name="Matsuo">{{cite journal |vauthors=Matsuo Y, Kido Y, Yamaoka Y |title=Helicobacter pylori Outer Membrane Protein-Related Pathogenesis |journal=Toxins |volume=9 |issue=3 |date=March 2017 |page=101 |pmid=28287480 |pmc=5371856 |doi=10.3390/toxins9030101 |doi-access=free }}</ref> When infection is persistent, the prolonged inflammation will become [[chronic gastritis]]. Initially, this will be non-atrophic gastritis, but the damage caused to the stomach lining can bring about the development of [[atrophic gastritis]] and ulcers within the stomach itself or the [[duodenum]] (the nearest part of the intestine).<ref name="Matsuo"/> At this stage, the risk of developing [[gastric cancer]] is high.<ref name="Marghalani"/> However, the development of a [[duodenal ulcer]] confers a comparatively lower risk of cancer.<ref name="Koga">{{cite journal |vauthors=Koga Y |title=Microbiota in the stomach and application of probiotics to gastroduodenal diseases |journal=World J Gastroenterol |volume=28 |issue=47 |pages=6702–6715 |date=December 2022 |pmid=36620346 |pmc=9813937 |doi=10.3748/wjg.v28.i47.6702 |doi-access=free }}</ref> ''Helicobacter pylori'' are [[Carcinogenic bacteria|class 1 carcinogenic bacteria]], and potential cancers include gastric [[MALT lymphoma]] and [[gastric cancer]].<ref name="Matsuo"/><ref name="Marghalani">{{cite journal |vauthors=Marghalani AM, Bin Salman TO, Faqeeh FJ, Asiri MK, Kabel AM |title=Gastric carcinoma: Insights into risk factors, methods of diagnosis, possible lines of management, and the role of primary care |journal=J Family Med Prim Care |volume=9 |issue=6 |pages=2659–2663 |date=June 2020 |pmid=32984103 |pmc=7491774 |doi=10.4103/jfmpc.jfmpc_527_20 |doi-access=free }}</ref> Infection with ''H. pylori'' is responsible for an estimated 89% of all gastric cancers and is linked to the development of 5.5% of all cases cancers worldwide.<ref name="Shin">{{cite journal |vauthors=Shin WS, Xie F, Chen B, Yu J, Lo KW, Tse GM, To KF, Kang W |title=Exploring the Microbiome in Gastric Cancer: Assessing Potential Implications and Contextualizing Microorganisms beyond H. pylori and Epstein-Barr Virus |journal=Cancers |volume=15 |issue=20 |date=October 2023 |page=4993 |pmid=37894360 |pmc=10605912 |doi=10.3390/cancers15204993 |doi-access=free }}</ref><ref name="Violeta">{{cite journal | vauthors = Violeta Filip P, Cuciureanu D, Sorina Diaconu L, Maria Vladareanu A, Silvia Pop C | title = MALT lymphoma: epidemiology, clinical diagnosis and treatment | journal = Journal of Medicine and Life | volume = 11 | issue = 3 | pages = 187–193 | date = 2018 | pmid = 30364585 | pmc = 6197515 | doi = 10.25122/jml-2018-0035 }}</ref> ''H. pylori'' is the only bacterium known to cause cancer.<ref name="Ruggiero">{{cite journal |vauthors=Ruggiero P |title=Use of probiotics in the fight against Helicobacter pylori |journal=World J Gastrointest Pathophysiol |volume=5 |issue=4 |pages=384–91 |date=November 2014 |pmid=25400981 |pmc=4231502 |doi=10.4291/wjgp.v5.i4.384 |doi-access=free }}</ref>

Extragastric complications that have been linked to ''H. pylori'' include [[anemia]] due either to iron deficiency or [[vitamin B12 deficiency]], [[Diabetes|diabetes mellitus]], cardiovascular illness, and certain neurological disorders.<ref name="WJG2020">{{cite journal |vauthors=Santos ML, de Brito BB, da Silva FA, Sampaio MM, Marques HS, Oliveira E, Silva N, de Magalhães Queiroz DM, de Melo FF |title=Helicobacter pylori infection: Beyond gastric manifestations |journal=World J Gastroenterol |volume=26 |issue=28 |pages=4076–4093 |date=July 2020 |pmid=32821071 |pmc=7403793 |doi=10.3748/wjg.v26.i28.4076 |doi-access=free |url=}}</ref> An inverse association has also been claimed with ''H. pylori'' having a positive protective effect against [[asthma]], [[esophageal cancer]], [[inflammatory bowel disease]] (including [[gastroesophageal reflux disease]] and [[Crohn's disease]]), and others.<ref name="WJG2020"/>

Some studies suggest that ''H. pylori'' plays an important role in the natural stomach ecology by influencing the type of bacteria that colonize the gastrointestinal tract.<ref name="Blaser 2006"/><ref name="Gravina">{{cite journal|vauthors=Gravina AG, Zagari RM, De Musis C, Romano L, Loguercio C, Romano M|date=August 2018|title=Helicobacter pylori and extragastric diseases: A review|journal=World Journal of Gastroenterology|type=Review|volume=24|issue=29|pages=3204–3221|doi=10.3748/wjg.v24.i29.3204|pmc=6079286|pmid=30090002 |doi-access=free }}</ref> Other studies suggest that non-pathogenic strains of ''H. pylori'' may beneficially normalize stomach acid secretion, and regulate appetite.<ref name="AckermanScientificAmerican">{{cite magazine | vauthors = Ackerman J | title = The ultimate social network | volume = 306 | issue = 6 | pages = 36–43 | date = June 2012 | pmid = 22649992 | doi = 10.1038/scientificamerican0612-36 | magazine = Scientific American }}</ref>

In 2023, it was estimated that about two-thirds of the world's population was infected with ''H. pylori'', being more common in [[developing countries]].<ref name="CDC2024">{{cite web |title=Helicobacter pylori {{!}} CDC Yellow Book 2024 |url=https://wwwnc.cdc.gov/travel/yellowbook/2024/infections-diseases/helicobacter-pylori |website=wwwnc.cdc.gov |access-date=20 October 2023 |archive-date=22 October 2023 |archive-url=https://web.archive.org/web/20231022070847/https://wwwnc.cdc.gov/travel/yellowbook/2024/infections-diseases/helicobacter-pylori |url-status=live }}</ref> The prevalence has declined in many countries due to [[Helicobacter pylori eradication protocols|eradication treatments]] with antibiotics and [[proton-pump inhibitor]]s, and with increased [[standards of living]].<ref name=Li2023/><ref name=HooiLai2017>{{cite journal | vauthors = Hooi JK, Lai WY, Ng WK, Suen MM, Underwood FE, Tanyingoh D, Malfertheiner P, Graham DY, Wong VW, Wu JC, Chan FK, Sung JJ, Kaplan GG, Ng SC | title = Global Prevalence of Helicobacter pylori Infection: Systematic Review and Meta-Analysis | journal = Gastroenterology | volume = 153 | issue = 2 | pages = 420–429 | date = August 2017 | pmid = 28456631 | doi = 10.1053/j.gastro.2017.04.022 | doi-access = free }}</ref>
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