UCSF

Objectives: The aims of the study were to investigate whether: 1) mutacin activity of MS against other oral streptococci; 2) sensitivity of mutans streptococci (MS) to bacteriocin produced by other closely related oral streptococci, namely S. sanguinis and S. gordonii; 3) and formation of extracellular insoluble glucans by MS are associated with MS transmission from mothers to their children.

Methods: Sixteen transmitted MS genotypes and 27 non-transmitted MS genotypes from 13 mothers who had transmitted MS to their children were included in the study. The sensitivities of MS to bacteriocin produced by S. sanguinis 10556 and S. gordonii 10558 were evaluated by bacterial overlaying assay. Mutacin activities of transmitted and non-transmitted MS against S. sanguinis 10556, S. gordonii 10558, S. mutans 25175, and S. sobrinus 6715 were also analyzed by similar assay. Anthrone-sulfuric acid colorimetric assay was used to quantify the extracted extracellular polysaccharide produced by transmitted and non-transmitted MS.

Results: Mutacin activities of transmitted MS genotypes against S. mutans and S. sobrinus were significantly higher than those of non-transmitted MS genotypes (Student t test, P<.05). There were no significant differences in mutacin activity against S. sanguinis and S. gordonii, nor on the sensitivity to bacteriocin produced by S. sanguinis and S. gordonii between transmitted or non-transmitted MS (Student t test, P>.05). The amount of glucan produced was not statistically related to MS transmission (Student t test, P<.05).

Conclusions: Higher mutacin activities against other S. mutans and S. sobrinus in maternally-transmitted MS genotypes may be an important contributing factor for their oral colonization in children, as compared to non-transmitted maternal strain. MS mutacin activities against S. sanguinis and S. gordonii, MS sensitivities to bacteriocin(s) produced by S. sanguinis and S. gordonii and MS glucans synthesis appear may not be related to transmission of MS in children.