Genetic bases for heterogeneity of Helicobacter pylori

Diversity, a characteristic of all living things, has long been recognized among microorganisms and has been well appreciated among bacteria1. For pathogenic microbes, those whose lifestyle results in injury to their larger hosts, a central notion is that these often represent clonal populations. In this context clonality represents a common ancestry, and a very close if not identical genetic relationship among the members of a group.