Oral Helicobacter pylori: Interactions with host and microbial flora of the oral cavity

The role of the oral cavity as a reservoir for Helicobacter pylori is still a controversial issue. There is a great number of articles indicating the presence of this pathogen in the oral cavity, but discrepancies among techniques for H. pylori detection and the variations in the patients tested often make it difficult to formulate a final verdict. Outer membrane proteins (OMPs) are one of the most important factors determining colonization of H. pylori in the oral cavity. Among them, the key role is attributed to BabA, SabA and NapA, all of which promote adherence and retention within this area. The oral cavity is characterized by the co-existence of numerous microorganisms which may potentially affect the physiology and morphology of H. pylori. The presence of coccoid-stimulating factors and relatively low levels of AI-2 in the early- to mid-stages of supragingival plaque allow dental H. pylori to colonize this niche as nonculturable spherical forms. On the other hand, subgingival plaque characterized by high numbers of periopathogens, capable of synthesizing high concentrations of AI-2, may favor the presence of mixed populations of spiral and coccoid H. pylori forms. This review article provides an up-to-date knowledge about the ability of oral H. pylori to interact both with the host and the local microflora of the oral cavity.