Helicobacter pylori: 20 years on

Abstract

This year marks the 20th anniversary of the culture of Helicobacter pylori in Perth, Australia, over Easter 1982. It is now known that the spiral, Gram-negative bacterium inhabits the stomach of more than 50% of humans. Although the new organism was only cultured in 1982 1 , the Italian anatomist Giulio Bizzozero had reported its manifestations in the scientific literature 100 years earlier 2 . He recognised that dogs harboured a gastric 'spirochaete' -certain proof that bacteria could survive in the acid-secreting stomach. Other investigators noticed that urease was usually present in the stomach of carnivorous animals such as dogs and cats 3 , findings that were extended to humans in 1950 4 . It was thought that all these facts were unrelated, and that gastric urease was actually secreted by the gastric epithelial cells, until Charles Lieber showed that it could be suppressed with tetracycline 5 , and Delluva showed that germ-free animals did not develop gastric urease 6 . The presence of spiral bacteria in the human stomach was reported several times, most notably by Freedberg in 1940 7 and Steer and Colin-Jones in 1975 8 , well before the bacteria were found to cause peptic ulcer and gastric cancer 1,9 . The history of H. pylori is the subject of a recent book, Helicobacter pioneers: firsthand accounts from the scientists who discovered helicobacters, 1892-1982 10 . Microbiology and taxonomyH. pylori is named because of its spiral or helical shape (Fig 1). The organism is approximately 0.6 µm thick, taking the shape of a flat spiral with 1.5 wavelengths. The organism has up to seven sheathed flagella. It prefers a microaerophilic (reduced oxygen) environment and can be cultured in gas jars with Campylobacter gas generating envelopes (Oxoid), or in carbon dioxide (CO 2 ) incubators at 37°C. The preferred agar media contain blood, with or without selective antibiotics, but media without blood can also be used 11 . The first helicobacter cultured was actually H. muridarum, a commensal organism colonising the crypts of the mouse caecum 12 . New helicobacter species are discovered regularly, and some are now regarded as human pathogens. Figure 2 summarises the taxonomy of the helicobacter genus as determined by sequencing the 16s ribosomal RNA 13 .According to observations from human and animal helicobacter infections, the genus has the capacity to colonise and cause inflammation in the stomach (H. pylori, H. heilmannii, H. mustelae

Helicobacter pylori invades the gastric mucosa and translocates to the gastric lymph nodes

“…3 H. pylori-induced active gastritis is triggered primarily by H. pylori attaching to epithelial cells. 4 Once attached to the gastric epithelial cells, H. pylori injects effector molecules into gastric epithelial cells or the lamina propria via a type IV secretion system. 5 The CagA effector molecule activates the epithelial expression of interleukin (IL)-8, which causes polymorphonuclear (PMN) cell infiltration.…”

Coupling Factors in Macromolecular Type-IV Secretion Machineries

“…In Helicobacter pylori , the microorganism responsible for gastritis, peptic ulcer and gastric cancer, a pathogenicity island (cagPAI), acquired by horizontal transfer, is the major determinant of virulence. This island codes for 31 Cag proteins, at least six of which may contribute to a type-IV system, which translocates in an example for direct trans-kingdom protein delivery the 150-kDa CagA antigen into gastric epithelial cells, where it is tyrosine phosphorylated [65,66]. There, the protein may interfere with the normal host cell signalling inducing pedestal formation, synthesis of proinflammatory cytokines and chemokines, like interleukin 8, cell spreading and motiliy, expression of the protooncogenes c fos and c jun, among other events [16,67,68], in a phenotype referred to as "hummingbird".…”

HELICOBACTER CETORUM INFECTION IN STRIPED DOLPHIN (STENELLA COERULEOALBA), ATLANTIC WHITE-SIDED DOLPHIN (LAGENORHYNCHUS ACUTUS), AND SHORT-BEAKED COMMON DOLPHIN (DELPHINUS DELPHUS) FROM THE SOUTHWEST COAST OF ENGLAND

“…Helicobacter infections in humans are associated with subclinical to clinically significant inflammation of the stomach, with a risk of cancer in a smaller percentage of those infected. Development of disease is influenced by many factors, including the expression of Helicobacter virulence factors, such as H. pylori cagA, which is associated with a higher risk of atrophic gastritis and cancer in humans (Marshall 2002).…”

“…Helicobacter has been implicated in conditions including typhlitis or colitis and gastritis in several species of mammals, and specifically, gastritis, peptic ulcer disease, and cancer in humans (Marshall 2002). Helicobacter infection in cetaceans was first reported in 2000 when novel Helicobacter species were isolated from Atlantic whitesided dolphins (Lagenorhynchus acutus) and characterized by analysis of partial 16S rRNA gene sequence from a short-beaked common dolphin (Delphinus delphis) with multifocal lymphoplasmacytic gastritis found stranded in Massachusetts, USA (Harper et al 2000).…”