Genetic and Transmission Analysis of Helicobacter pylori Strains within a Family

摘要

To look for evidence of intrafamilial infection, we isolat-ed 107 Helicobacter pylori clones from biopsied specimenstaken from both parents and four children. We comparedthe sequences of two housekeeping genes (hspA andglmM) from these clones with those of 131 unrelatedstrains from patients living in different geographic regions.Strain relationships within the family were determined byanalyzing allelic variation at both loci and building phyloge-netic trees and by using multilocus sequence typing. BothhspA- and glmM-based phylogenetic trees showed EastAsian and African branches. All samples from family mem-bers showed natural mixed infection. Identical alleles foundin some strains isolated from the children and parents, butnot in the strains isolated from unrelated patients, demon-strated that strains have circulated within the family.Several mechanisms, such as point mutations, intragenicrecombination, and introduction of foreign (African) alleles,were shown to enhance strain diversity within the family