Familial clustering of the Streptococcus mutans cryptic plasmid strain in a dental clinic population

Of Streptococcus mutans strains from 100 pedodontic patients, 13% contained the common cryptic plasmid. Family members of four plasmid-positive patients harbored plasmid-positive S. mutans at a significantly greater frequency compared with the pedodontic population, but there was not a one-to-one correlation of strains between mothers and children.