title: [Pathophysiology of Helicobacter pylori infections].
abstract: Helicobacter pylori is the causative factor of chronic gastritis and ulcers of duodenum and stomach and relates to mucosa-associated lymphoid tissue (MALT) lymphomas. Host factors, bacterial factors and dietary habits conceivably play a part in the more severe mucosal lesions induced by H. pylori. H. pylori is a heterogeneous bacterial species, the various types differing in possession of a locus with genes coding for products that may intensify the inflammatory reaction. The cytotoxin-associated gene (cagA) protein is a marker for this locus; this protein and the vacuolating-associated cytotoxin A are clearly related to the ulcerative disease. Patients may be colonized by a mixed population of H. pylori consisting of cagA-positive and cagA-negative H. pylori. Also, a patient may be infected by a mixed population of H. pylori sensitive and resistant to metronidazole. Accordingly, a substantial part of the H. pylori population in a patient should be examined to arrive at an adequate conclusion concerning the production of H. pylori factors that may relate to a particular clinical picture and to the sensitivity to antibiotics of the H. pylori.
authors.affiliation: Afd. Medische Microbiologie, Academisch Medisch Centrum, Amsterdam. a.vanderende@amc.uva.nl
authors.forename: A
authors.initials: A
authors.lastname: van der Ende
authors.forename: R W
authors.initials: RW
authors.lastname: van der Hulst
authors.forename: G N
authors.initials: GN
authors.lastname: Tytgat
authors.forename: J
authors.initials: J
authors.lastname: Dankert
mesh_terms: D004381:Duodenal Ulcer / Q000209:etiology; D005756:Gastritis / Q000209:etiology*; D020022:Genetic Predisposition to Disease; D016481:Helicobacter Infections / Q000209:etiology*; D016480:Helicobacter pylori / Q000302:isolation & purification / Q000472:pathogenicity*; D006801:Humans; D018442:Lymphoma, B-Cell, Marginal Zone / Q000209:etiology; D010437:Peptic Ulcer / Q000209:etiology; D012008:Recurrence; D012307:Risk Factors; D013276:Stomach Ulcer / Q000209:etiology