Method: 17 oligonucleotide probes targeting 30 uncultivated/unrecognized taxa were employed. Probes for 4 cultivated taxa and a Eubacterial probe were also used. Subgingival biofilm samples from 8 periodontitis (n=56) and 4 periodontally healthy (n=28) subjects were individually examined using the RNA-oligonucleotide quantification technique. Signals were converted to picomolars (pM) of RNA based on standard curves. Significance of differences between groups was tested using the Mann-Whitney test. Oral taxon (OT) designations were used in accord with the Human Oral Microbiome Database.
Result: The levels of P.gingivalis, F.nucleatum and the uncultivated/unrecognized taxa Synergistetes (OT 363;453;452), TM7 (OT 346;349), Desulfobulbus (OT 041), Bacteroidetes sp (OT 274) were significantly higher (p<0.01) at sites from periodontitis subjects compared to sites from healthy subjects. When pockets ≥4mm were compared to shallower sites, significantly higher levels of Streptococcus sp (OT 070;071), Bacteroidetes sp (OT 274) Selenomonas sp (OT 134;442), Synergistetes (OT 360), P.gingivalis, and F.nucleatum were observed (p<0.001). Synergistetes (OT 360), TM7 (OT 346;349), Capnocytophaga sp (OT 335), Desulfobulbus (OT 041) and Selenomonas sp (OT 134;442) were the most frequently detected uncultivated/unrecognized taxa in sites from periodontitis subjects (42%, 36%, 34%, 28% and 26% of sites, respectively). While all taxa probed for were detected in periodontitis subjects, 17 uncultivated/unrecognized taxa and 2 cultivable species were never found in sites from healthy subjects, including P.gingivalis.
Conclusion: The uncultivated/unrecognized taxa Streptococcus sp (OT 070;071), Bacteroidetes sp (OT 274) Selenomonas sp (OT 134;442), Synergistetes (OT 360), Synergistetes (OT 363;453;452), TM7 (OT 346;349), Desulfobulbus (OT 041), Capnocytophaga sp (OT 335) might be associated with periodontal diseases.