Ribosomal RNA gene restriction patterns of Helicobacter pylori: analysis and appraisal of Hae III digests as a molecular typing system.

Ribosomal RNA gene restriction patterns (ribopatterns) of 162 strains of Helicobacter pylori from 93 patients were studied to assess their suitability for use as the basis of a molecular typing system. Computer-assisted numerical analysis of Hae III ribopatterns of 122 strains from 9 countries in 4 continents showed that almost every strain had a distinct and unique ribopattern and only strains from the same individual were genomically matched in all bands or with minor (1-2 band) differences. Hae III ribopatterns offered high typability and reproducibility but were too discriminatory for large-scale epidemiological typing purposes because no rational basis for grouping strains was evident. In contrast, composite band profiles based on 21 band loci within the Hae III ribopatterns, which were used to compare strain sets selected on toxigenicity and geographical origin, were more conserved. Minor differences between some strain sets in several band loci were detected but generally the composite profiles were a reproducible feature of H. pylori. We conclude that Hae III ribopatterns provide an excellent fingerprint for small-scale studies of genomic variation in defined populations, such as sequential patient isolates, but are too specific for general typing of H. pylori.