Genetic variability determinants of Helicobacter pylori: Influence of clinical background and geographic origin of isolates

Helicobacter pylori has an unusual pattern of genetic variation, which comp licates research on this organism, To gain a better understanding of the fo rces behind this phenomenon, the extent to which recombination and single p oint mutations affect genetic variability in H. pylori was quantified and t he influence of both geographical distance and clinical background were ass essed. Site-directed restriction-endonuclease digestion of 2 gene fragments was performed on 168 isolates from Montreal and Berlin, Allelic diversity was found to be much higher for H. pylori than for other bacterial species. This finding is consistent with those of previous studies on H. pylori tha t were conducted using other techniques. However, nucleotide diversity was within the range reported for other bacterial species. Phylogenetic analysi s found no grouping of strains with clinical background or geographical ori gin. Recombination at a rate that resulted in linkage equilibrium within ge nes can explain these observations.