Helicobacter pylori as a witness of the world's popularisation: a population genetic review for specialist of internal medicine

According to some estimates, 60% of the world's population is infected by Helicobacter pylori (H. pylori). Strains of bacteria from different areas of the world are not uniform. Their genetic diversity is more significant than those of other bacteria are which has been examined until now.

The bacterial DNA sequence is more heterogeneous than human mitochondrial and chromosome Y markers, which has been examined in population genetic surveys. Infections by H. pylori start in childhood predominantly from the family environment. Therefore, parental H pylori genetic pattern is inherited. Differences in the H. pylori genetic pattern are constantly present for centuries as shown by an investigation conducted in a Northern Indian city. This study proved that despite the close contact between Muslim and Buddhist religious groups the bacteria maintain their characteristic genetic pattern. It seems that this feature is more consistent and useful than classical population genetic markers.

From the non-random genetic changes that accumulate during a certain period, it is possible to estimate the age of a bacterial strain. It seems that H. pylori is an ancient strain, which has accompanied migrating population for a long time.

Bacterial colonies can be separated to seven groups from different geographical regions. These have arisen from four ancient clones. The clones are from Africa, the Middle East, middle Asia and from the Far East.

Comparison of bacterial genetic changes with that of the ethnical migration, it allows reconstruction of the human race migration through continents.

Genetic changes are useful not for only population genetic reviews but also explain the variability of disease caused by bacteria. This pinpoints an extreme capability of accommodation to different environments and explains resistance to antibacterial treatment.