H. pylori defies the physicochemical defence of gastric mucosa mechani
sms using his mobility, his adapted acid metabolism and his adherence
to the gastric epithelium, The immune-biological defence of the host i
s unable to eliminate the infection Helicobacter infection always lead
s to gastritis. Progression to more serious disorders depends on the H
elicobacter strain, on host factors and on the environment. Helicobact
er plays an essential role in the pathogenesis of gastric and duodenal
ulcers and of MALT-lymphoma. H. pylori contributes to the development
of gastric carcinoma. Its role in functional dyspepsia is controversi
al; its role in extra-gastroduodenal diseases such as myocardial infar
ction is highly controversial.