ULTRASMALL BACTERIA AND PERIODONTITIS – THE NOVEL LINK

Abstract

Periodontal diseases are triggered by an interaction between bacterial components of tooth associated biofilms and host immune response mechanisms. Candidate phyla radiation (CPR) bacterial group is a recently identified, but highly diverse and abundant group of ultrasmall bacteria. CPR group includes Absconditabacteria (SR1), Gracilibacteria (GN02) and Saccharibacteria (TM7). Real time PCR and metagenomics based techniques are also employed to detect CPR species. TM7 organisms has been detected in periodontitis patients, HIVpositive patients with necrotizing ulcerative periodontitis, smokers with periodontitis, aggressive periodontitis cases and in mature plaque samples procured from orthodontic treatment undergoing individuals. It is found that TM7 isolate grow as short rods or cocci in dual-species biofilms with Porphyromonas gingivalis, Prevotella intermedia, Parvimonas micra or Streptococcus gordonii. The positive association of ultrasmall bacteria or CPR microorganisms with periodontal diseases spotlights the capacity of ultrasmall bacteria to modulate the immune response. The CPR microbiome is enriched with virulence factors and is adapted to a parasitic lifestyle that leads to disrupted host homeostasis. This makes the individual susceptible to periodontal tissue destruction. In future, we should instigate researches to know more about the actions and properties of ultrasmall bacteria and their association with periodontal diseases. KEYWORDS: ultrasmall bacteria, periodontitis, Candidate Phyla Radiation (CPR) group, periodontal microbiology