Implantation of transformant strains of the bacterium Streptococcus sanguis into adult human mouths.

Streptococcus sanguis strains isolated from dental plaque of 12 subjects were screened for their ability to undergo genetic transformation using a streptomycin-resistance marker. All subjects harboured at least one transformable strain. Eight of the subjects were implanted with transformant strains originally isolated from their own mouth, whereas four subjects received bacteria from other donors. The Strep. sanguis transformants became successfully implanted; their oral levels remained virtually unchanged during the 3-month experimental period. Their oral establishment did not seem to be related to whether the subjects were implanted with their own transformant strains or not. The implanted Strep. sanguis could be recovered both from teeth, oral soft tissues and throat.