Role of Helicobacter pylori coccoid forms in infection and recrudescence

Abstract Helicobacter pylori is a spiral Gram-negative bacillus, which colonizes the human stomach and plays a key role in the pathogenesis of a number of gastroduodenal diseases. However, when expose to environmental stressed conditions, such as increased oxygen tension, extended incubation and exposure to antibiotics, H. pylori is able to entering the viable but nonculturable state, in which the bacterium modifies its morphology from a spiral to coccoid form, as a manifestation of cell adaptation to these adverse conditions. In gastric tissues, viable coccoid forms may remain latent for long time and retain virulence factors, so these forms possibly contribute to the treatment failures and recurrence of H. pylori infection and gastroduodenal diseases as well. In this review, we will discuss several aspects of cellular adaptation and survival of H. pylori , antibiotic susceptibility and virulence of coccoid forms and its involvement with recrudescence.