Application of inhibitor typing in a study of the transmission and retention in the human mouth of the bacterium Streptococcus salivarius.

Inhibitor production (P)-typing was used as a strain marker in epidemiological studies of Streptococcus salivarius. 43 per cent of 180 adult subjects had inhibitory Strep. salivarius strains as components of their oral microbiota. Strains of 13 different P-type patterns were detected and strains of different P-types often co-existed in the same subject. Adults from whom inhibitor-producing Strep. salivarius strains had been isolated retained their characteristic bacteriocinogenic strains over a 3-yr period. A specific Strep. salivarius-inhibitor screening method was used to study oral acquisition of Strep. salivarius by 14 newborn babies. Initially the babies were colonized by a wide variety of strains, many of which were not detected in the mothers' mouths. By the fifth day of life, strains with P-types identical with those in the mother had often become established as quantitatively prominent members of the babies' Strep. salivarius population.