Intraspecies interactions of impact biofilm architecture and virulence determinants in childhood dental caries.

Early childhood dental caries (ECC) is the most common chronic disease among children with a heavy disease burden among low socioeconomic populations. is most frequently associated with initiation of ECC. Many studies report children with multiple strains (i.e., genotypes) having greater odds of developing ECC, studies investigating intraspecies interactions in dental caries are lacking. In this study, the impact of intraspecies interactions on cariogenic and fitness traits of clinical isolates are investigated using and approaches. Initially clinical isolates of 10 children from a longitudinal epidemiological study were evaluated. strains (G09 and G18, most prevalent) isolated from one child were used for subsequent analysis. Association analysis was used to determine if presence of multiple genotypes within the first-year of colonization was associated with caries. Biofilm analysis was performed for single and mixed cultures to assess cariogenic traits, including biofilm biomass, intra-polysaccharide, pH, and glucan. Confocal Laser Scanning Microscopy (CLSM) and time-lapse imaging were used to evaluate spatial and temporal biofilm dynamics, respectively. A model was used to assess colonization . Mean biofilm pH was significantly lower in co-cultured biofilms as compared with monoculture biofilms. Doubling of biofilms was observed by CLSM and colonization in for co-cultured . Individual strains occupied specific domains in co-culture and G09 contributed most to increased co-culture biofilm thickness and colonization in . Biofilm formation and acid production displayed distinct signatures in time-lapsed experiments.