Relationship between periodontitis-associated subgingival microbiota and clinical inflammation by 16S pyrosequencing

Aim: To analyse the relationship between the chronic periodontitis-associated subgingival microbiota and clinical inflammation. Material and Methods: Sixty subjects with generalized chronic periodontitis participated in this study. Patients were divided into two groups according to their bleeding on probing (BOP) scores: BOP-1 group (mean scores <= 50% in sampled sites) and BOP-2 group (mean scores >50%). Subgingival bacterial samples from periodontal patients were studied by pyrosequencing PCR products of the 16S rRNA gene and by real-time PCR. Results: In all the analysed subgingival samples, 102 bacterial genera and 203 species (from 41 genera of interest) were identified. Rarefaction curves showed a greater number of bacterial species in samples from BOP-2 group compared to BOP-1 group. The BOP-1 group had significantly higher abundance percentages of Anaeroglobus (especifically, A. geminatus), Capnocytophaga (especifically C. gingivalis), TM7 and Veillonella. The BOP-2 had significantly higher abundance percentages of Desulfobulbus (especially D. propionicus), Eubacterium (especially E. saphenum), Filifactor alocis, Streptococcus constellatus, Tannerella (especially, T. forsythia) and Treponema. Conclusion: 16S pyrosequencing revealed that increased inflammation, at sites with periodontitis, is associated with a more diverse subgingival microbiota and specific changes in the bacterial composition, involving "established" periopathogens, symbionts and novel low-abundance pathobionts.