Intrafamiliar transmission patterns of Helicobacter pylori strains by using molecular typing

Introduction: The spread of Helicobacter pylori infection is still a subject of research. Family transmission is the most important transmission way in developed countries.
Aim: To assess of transmission within family on the base of genetic typing of H. pylori strains isolated from family members.
Material and methods: Altogether 55 members from 22 families with diagnosed gastritis connected with H. pylori infection were included into the study. Bacteria genetic material was isolated from the stomach biopsy specimens with the use of NucleoSpin®Tissue kit (Macherey-Nagel). Genes: glmM, cagA, cagE, iceA underwent polymerase chain reaction during analysis of H. pylori strains and multiplex PCR reaction for vacA (s1/s2 + m1/m²) was performed.
Results: Gastritis caused by H. pylori infection was diagnosed in 55 members of 22 families, including 13 mothers, 11 fathers and 30 offspring. Parents’ age varied from 31 to 54 years (mean age 39.1 years), but offspring’s age varied from 4 to 26 years (mean age 11.9 years). Unanimity of H. pylori genetic types were found only in 18 from 44 pairs of persons who are the members of the same family (40.9%). Most often infection with the same genetic type of H. pylori was proved in pairs mother-child (70.6%). Only one of seven married couples was infected with the same genetic type of bacteria (14.3%). Infection with the same H. pylori type was observed similarly rarely between father and his child (27.3%), but also among siblings (22.2%). Only in three among 11 families with three persons infected with H. pylori all family members included in the study (mother and two children two times, mother-father-son once) were infected with the same genetic type of bacteria. The presence of cagA gene was found in 45 persons of 55 family members (81.8%) infected with H. pylori, cagE gene was noted in 13 of them (23.6%), iceA gene – in 7 of them (12.7%), vacAs gene – in 17 of them (30.9%), but vasAm gene – in 7 of them (12.7%).
Conclusions:
1) Genetic typing of H. pylori strains isolated from family members confirms essential role of mother in infection transmission to children.
2) Infection of other family members, but particularly married couples seem to be less important in infection transmission.