Streptococcus sobrinus

This Gram positive coccus is most frequently found in pairs and often long chains of spherical or ovoid cells. Cells are catalase negative and exhibit facultatively anaerobic metabolism. Most frequently isolated from the surface of human teeth, and closely associated with dental caries. Also found in the mouths of rats.  Production of a sucrose-based capsular material allows formation of biofilm on teeth and facilitates growth leading to dental caries. This augments the production of dextran capsules by other streps to create a complex biofilm that is not easily removed.