Oral Microbial Ecology of Selenomonas noxia and Scardovia wiggsiae

Objectives: Selenomonas species such as S. noxia are associated with poor oral health and oral prevalence of this organism may be useful as a biomarker to determine patient oral health. Current studies are now revealing novel insights into the epidemiology of the newly discovered oral cariogenic organism Scardovia wiggsiae (SW), although few studies have explored the oral microbial ecology with respect to this oral pathogen. Based upon the lack of information regarding the oral microbial ecology, the primary objective of this study was to screen an existing saliva repository to more accurately assess the microbial flora present (or absent) including SN and SW.

Experimental Methods: Previously collected saliva samples were evaluated for the DNA isolation and qPCR screening protocol. A total of 42 samples were identified and processed from both pediatric (n=28/42 or 67%) and adult (n=14/42 or 33%) patients.

Results: The results of this screening demonstrate that of the SW-positive samples (n=27/42 or 64%) none harbored the oral microbe Selenomonas noxia (SN). Conversely, SN was identified only within the subset of SW-negative samples (n=15/42 or 35%). In addition, although Aggregatibacter actinomycetemcomitans (AA) was only present in a small subset of samples – this organism was only found among SW-positive samples. Other organisms, including T. forsythia (TF), and F.nucleatum (FN) were present in both SW-positive and SW-negative samples although their prevalence differed greatly.

Conclusions: This study may be the first to present oral microbial data which suggest SW may participate in direct or indirect bacterial interactions that influence the potential for other organisms to flourish within the oral microbiome. These data suggest that SN and SW may occupy distinct, non-overlapping niches, which may differ significantly from the interactions observed with AA, FN, and TF. Further research will be needed to more fully elucidate these interactions and to explore the potential ramifications for oral microbial ecology and the implications for predictive saliva screening.