[Helicobacter pylori. I. Morphology, biochemistry, antigenic profile and correlated diseases].

Infection by Helicobacter pylori (HP) occurs all over the world and is related to the socio-economic development of the subject's country of residence and age. Various strains of HP can be identified on the basis of the microbiological characteristics of the bacterium and, in particular, or its antigenic profile, while the virulence factors are responsible for the damage that HP can cause. The virulence factors include components (flagellum and adhesin) and substances produced by bacterium (enzymes and cytotoxins), the most important among which are urease and the cytotoxins, CagA and VacA. It is the association of these virulence factors that is responsible for the different pathologies to which HP-positive subjects are prone. The link between HP and gastritis, peptic ulcer and gastric cancers (adenocarcinoma and lymphoma) is now proven. Whether there is a link between HP and RAP in young children is still a matter for debate; some Authors claim that there is, while others refute it.