Biotypes and DNA fingerprints of cytotoxigenic Helicobacter pylori from patients with gastritis and peptic ulceration in Italy.

Variations in biotypic and DNA characteristics of 21 strains of Helicobacter pylori from patients in central Italy with histologically defined gastritis and/or peptic ulcers were studied. The strains had the same preformed enzyme biotype but differed in motility and cytotoxigenic activity. The presence or absence of these two characteristics were closely associated in 73% of strains and were used to define three phenotypic subsets. Strains of subset 1 (Mot+ Tox+) were most common (52%) particularly amongst patients with peptic ulceration (64%). H. pylori had unique HaeIII and HindIII ribopatterns but no one ribopattern or single band within a ribopattern was characteristic of any particular phenotypic subset. H. pylori from patients with gastritis were genomically as heterogeneous as those from patients with ulcers. Plasmid DNA was detected in four strains (25%) and although three of these were of the same biotype (phenotypic subset 1), there was no general association apparent between plasmid presence and cytotoxic activity. It was concluded that motility was a useful additional feature for biotyping of H. pylori.