Screening a Saliva Repository for Scardovia wiggsiae and Streptococcus mutans: A Pilot Study

Abstract

Introduction: Many studies have evaluated the prevalence of cariogenic pathogens among dental school patients, most notably the Gram-positive organism Streptococcus mutans (SM). Recent evidence has suggested another cariogenic pathogen Scardovia wiggsiae (SW) may also be present in the oral flora of a smaller subset of dental patients.  Objective: Few studies to date have examined the corresponding prevalence of both SM and SW within the same patient samples, therefore the main objective of this study was to evaluate the presence of these cariogenic organisms within a dental school-based setting. Experimental Methods: Screening was facilitated using DNA extracted from a pre-existing patient saliva repository and processed using qPCR.  SW-positive (n=27) and SW-negative (n=15) samples were subsequently screened for the presence of SM. The samples were nearly evenly divided between males and females (45%, 55%, respectively) and were mostly Hispanic minorities (n=22/42 or 52%). Results: This analysis revealed that 45% of samples (n=19/42) also harbored SM. More detailed analysis revealed that the vast majority of SM-positive samples (n=15/19 or 79%) were derived from SW-positive samples, while only a small percentage of SM-positive samples (n=4/19 or 21%) were derived from SW-negative samples.  Conclusions: The limited numbers of studies available regarding SW prevalence have suggested that SW and SM may inhabit similar and overlapping niches within the oral microbiome. In fact, some work has suggested the potential for competition and interactive inhibition between these organisms within the oral cavity. The preliminary data from this pilot study suggest SM and SW may, in fact, be present in the same patients and may not therefore be exclusively competitive – at least in this cross sectional study.  However, due to the large differences observed among these samples, further research will be needed to further elucidate and validate these findings.