Helicobacter pylori: Balance and imbalance

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Diversity of Helicobacter pylori A large body of evidence indicates that H. pylori has been present in the stomach of humans and our antecedents for millions of years and has adapted to survive in this acidic environment Factors that contribute to the persistence of H. pylori include its adaptation to noxious stimuli and the considerable phenotypic diversity in antigen expression between strains from different hosts. In addition, there appears to be substantial diversity in the expression of Lewis antigens between organisms taken from any one individual. Evidence suggests that a host is colonized by a population of clonal variants, probably mutants of one another. Furthermore, data indicate that the host Lewis phenotype selects for H. pylori Lewis expression. Relationship between H. pylori type and cancer Overall, there seems to be homeostasis between H. pylori and its host: evolution has selected for hosts that do not try to eliminate the microbe and for microbes that do not kill the host. In terms of its relationship to human disease, the incidence of H. pylori colonization in the population is declining, and this parallels the decline in ulcer disease and in cancers of the distal stomach. In contrast, the incidence of adenocarcinomas of the proximal stomach and oesophagus are on the increase, possibly due to the increase in gastro-oesophageal reflux disease. Status of cytotoxin-associated gene (cag) is an important determinant of the degree of inflammation and virulence of an H. pylori strain, and accumulated data lead to the hypothesis that carriage of capA-positive H. pylori strains may increase the incidence of cancers of the lower stomach and duodenum, but may be protective against cancers of the proximal stomach and lower oesophagus.

Original languageEnglish (US)
Pages (from-to)S15-S18
JournalEuropean Journal of Gastroenterology and Hepatology
Issue numberSUPPL. 1
StatePublished - Jun 1998
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Hepatology
  • Gastroenterology


  • Gastro-oesophageal reflux disease
  • Helicobacter pylori
  • Homeostasis
  • Lewis antigens
  • Peptic ulcer

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