title: Helicobacter pylori and non-Helicobacter pylori bacterial flora in gastric mucosal and tumour specimens of patients with primary gastric lymphoma.
abstract: There is an association between Helicobacter pylori (H. pylori) and gastric mucosa-associated lymphoid tissue (MALT) and MALT lymphoma. Histologically, mainly non-specific stains are used to detect H. pylori, such as haematoxylin-eosin (HE) or modified Giemsa (MG). In this study, both a MG and a specific immunohistochemical stain (IMM) for H. pylori (Dako B471) were performed on sequential slides of resected material containing tumour and non-tumorous gastric mucosa from patients with primary gastric lymphoma (n = 52). Special attention was paid to the presence of non-H. pylori bacterial flora diagnosed by a positive MG (according to form and localization) and a subsequently negative IMM. On all slides, bacterial density was scored semiquantitatively (grades 0, 1, 2, 3). In total, 32 (61.5%) patients were H. pylori positive using IMM and 34 (65.4%) were non-H. pylori positive using MG. In 24 out of the 34 patients, the non-H. pylori flora consisted mainly of cocci in combination with rods in 15 patients, mostly in minor quantities; in another 10 patients, high numbers of both cocci and different types of rods were present. Most non-H. pylori bacteria were localized superficially, although in 22 patients minor quantities of non-H. pylori were also seen in the glandular lumina. After all of the patients had been analysed, no differences in the density of H. pylori and of non-H. pylori flora were found. Only when comparing patients who had a small-cell lymphoma with those who had a large-cell lymphoma was a significantly higher density of H. pylori found in the corpus mucosa of large-cell lymphomas and a higher prevalence of non-H. pylori was found in tumours, in antrum or corpus, of patients with large-cell lymphomas. In conclusion, with joint evaluation using MG and a H. pylori-specific immunohistochemical stains, the proportion of H. pylori-positive gastric lymphoma patients was lower than in most previous studies but other bacteria were found in a relatively high proportion. The role of the non-H. pylori intragastric bacterial flora identified in this study has to be further elucidated in the aetiopathogenesis of primary gastric lymphoma.
authors.affiliation: Department of Gastroenterology, University Hospital Maastricht, The Netherlands.
authors.forename: D
authors.initials: D
authors.lastname: Jonkers
authors.forename: I
authors.initials: I
authors.lastname: Gisbertz
authors.forename: A
authors.initials: A
authors.lastname: de Bruine
authors.forename: F
authors.initials: F
authors.lastname: Bot
authors.forename: J W
authors.initials: JW
authors.lastname: Arends
authors.forename: E
authors.initials: E
authors.lastname: Stobberingh
authors.forename: H
authors.initials: H
authors.lastname: Schouten
authors.forename: R
authors.initials: R
authors.lastname: Stockbrügger
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001419:Bacteria / Q000302:isolation & purification*; D005260:Female; D005753:Gastric Mucosa / Q000382:microbiology*; D016480:Helicobacter pylori / Q000302:isolation & purification*; D006801:Humans; D008223:Lymphoma / Q000382:microbiology*; D008297:Male; D008875:Middle Aged; D013274:Stomach Neoplasms / Q000382:microbiology*