Genetic and transmission analysis of Helicobacter pylori strains within a family.

To look for evidence of intrafamilial infection, we isolated 107 Helicobacter pylori clones from biopsied specimens taken from both parents and four children. We compared the sequences of two housekeeping genes (hspA and glmM) from these clones with those of 131 unrelated strains from patients living in different geographic regions. Strain relationships within the family were determined by analyzing allelic variation at both loci and building phylogenetic trees and by using multilocus sequence typing.