Streptococcus mutans Strain Variability and Dental Caries

Objectives: Streptococcus mutans (SM) is considered the major microorganism involved in the etiology of dental caries. Previous studies have yielded conflicting results regarding strain variability and the cariogenic status of the subjects. If differences in strain distribution and/or virulence potential can be linked to caries, an analysis of host SM strains might provide a more effective long-term caries risk assessment. We sought to examine the genetic diversity of SM strains isolated from two Appalachian families, a population with endemic high caries rates. Methods: From the population-based cohort of families ascertained by the Center for Oral Health Research in Appalachia plaque samples were obtained from a family with low caries incidence and another family suffering from high levels of dental decay. A code protected the clinical status of the families so that our study was blinded. Variability among SM isolates was determined by arbitrary-priming polymerase chain reaction. Results: The low-caries family (six family members) had one individual with a single SM amplitype. The high-caries family (five family members) showed two individuals each with multiple distinct SM amplitypes, some of which were shared between the two individuals. Conclusion: Results to date show a dramatic difference in strain variability between families of different cariogenic status, with more variability and more strains seen in the high caries family. Further investigation of additional families will be necessary to determine whether this pattern remains consistent. NIH Grant#R01-DE014889