Using Macro-Arrays to Study Routes of Infection of Helicobacter pylori in Three Families

Abstract

BackgroundAnalysis of the evolutionary dynamics of Helicobacter pylori allowed tracing the spread of infection through populations on different continents but transmission pathways between individual humans have not been clearly described.Materials and MethodsTo investigate person-to-person transmission, we studied three families each including one child with persistence of symptoms after antibiotic treatment. Ten isolates from the antrum and corpus of stomach of each family member were analyzed both by sequencing of two housekeeping genes and macroarray tests.ResultsA total of 134 (8.4%) out of the 1590 coding sequences (CDSs) tested, including cag PAI and insertion sequences, were present in some but not all isolates (and are therefore defined as variable CDSs). Most of the variable CDSs encoded proteins of unknown function (76/134) or were selfish DNA including that encoding restriction/modification enzymes (13/134). Isolates colonizing the stomach of one individual can vary by point mutations, as seen in hspA, or by the gain or loss of one to five CDSs. They were considered as (genetic) variants. The phylogenetic clustering of gene profiles obtained on macro-arrays allowed identifying the different strains infecting families. Two to five strains circulated within a family. Identical strains were present in at least two members of all three families supporting the accepted model of intrafamilial transmission. Surprisingly, the mother was not implicated in the transmission of H. pylori in the two French families. Sibling-to-sibling transmission and acquisition of H. pylori from outside the family appeared to be probable in the transmission pathways.ConclusionMacroarray analysis based on previously selected CDSs gives a comprehensive view of the genome diversity of a pathogen. This approach combined with information on the origin of the hspA and glmM alleles revealed that Helicobacter pylori infection may be acquired by more diverse routes than previously expected.

Helicobacter pylori Genomic Microevolution during Naturally Occurring Transmission between Adults

“…Most of the variably present genes were coding for proteins with unknown function or for restriction and modification enzymes and only very few outer membrane protein genes [20], unlike genomic changes during chronic infection, a significantly high proportion of which affected OMP genes [6]. However, these differences might be due to the technical limitations of array studies that are usually not sensitive enough to detect point mutations or recombinant DNA fragments.…”

Environmental risk factors affecting transmission of Helicobacter pylori infection in Egypt

“…Sari et al (2008) provided a theoretical explanation for the above findings: they stated that bad sanitary conditions may facilitate transmission of infection among family members and increase the prevalence of the H. pylori organism among them. Raymond et al (2008) described the role of intrafamilial transmission of infection in a study carried out on patients who suffered from various clinical diseases in Africa, Asia, and Europe. The results of the present study showed a highly statistically significant relationship between H. pylori infection and the absence of clean running water, safe sewage disposal, the presence of flies in the house, not washing vegetables before eating them, and sharing eating utensils and towels between family members.…”

Infection à Helicobacter pylori : bonnes pratiques

“…La même observation peut être faite dans les pays émergents où les plus jeunes sont beaucoup moins souvent infectés que les plus anciens. Si l'on peut s'attendre à la présence de la même souche bactérienne au sein d'une famille de génération en généra-tion, ce concept semble moins vrai dans les pays à forte prévalence, sans doute du fait de la multiplication des expositions [6].…”