Prevalence and diversity of Synergistetes taxa in periodontal health and disease

Background and Objective Members of the phylum Synergistetes have previously been identified within periodontitis subgingival plaque and are considered putative periodontopathogens. This study compared the diversity of subginigval Synergistetes in a cohort of subjects with periodontitis (n=10) vs. periodontitis-free controls (n=10). Material and Methods Pooled subgingival plaque samples from all deep periodontal pockets or all sulci were collected from the periodontitis and periodontitis-free subjects, respectively. Bacterial 16S rRNA genes were PCR-amplified from purified subgingival plaque DNA using a Synergistetes selective' primer set. PCR products were cloned and sequenced to analyze the prevalence and diversity of Synergistetes operational taxonomic units (OTUs) present in plaque samples of both subject groups. Results A total of 1030 non-chimeric 16S rRNA clones were obtained, of which 162 corresponded to members of the phylum Synergistetes. A significantly larger number of Synergistetes clones were obtained from periodontitis subgingival plaque than from periodontitis-free controls (25.4% vs. 5.9%, p<0.001). All Synergistetes clones corresponded to cluster A oral Synergistetes, and fell into 31 OTUs (99% sequence identity cut-off). Twenty-nine Synergistetes OTUs were detected in the periodontitis group while eight were detected in the periodontitis-free group (p<0.001). Five Synergistetes OTUs; including one OTU corresponding to the recently-characterized species Fretibacterium fastidiosum, were more prevalent in the periodontitis subjects (p<0.05). Conclusion OTUs belonging to oral Synergistetes cluster A were more readily detectable and were more diverse in subgingival plaque from periodontitis subjects compared with periodontitis-free controls. Specific Synergistetes OTUs appear to be associated with periodontitis.