PRODUCTION OF GLUCOSYLTRANSFERASES BY CLINICAL MUTANS STREPTOCOCCAL ISOLATES AS DETERMINED BY SEMIQUANTITATIVE CROSS-DOT ASSAY

Forty-four clinical isolates of mutans streptococci were examined by a semiquantitative cross-do; assay for in vitro production of glucosylt ransferases GTF-I, GTF-SI and GTF-S of Streptococcus mutans, and GTF-I of Strep. sobrinus, using monospecific antibodies. The isolates were obtained From 12 1.5- to 3-year old children, six caries-active and si x caries-free, and from their mothers. The isolates were selected orig inally from 243 isolates and they represented 35 genetically distinct types as analysed by serotyping and ribotyping. 27 isolates were of se rotype c, nine of serotype e and eight of serotype g. Mother-child pai rs shared nine ribotypes, suggesting vertical transmission. The result s showed that, when cultured in Todd-Hewitt broth supplemented with 1% glucose, all Strep. mutans isolates produced GTF-I and GTF-S and all except two produced GTF-SI of Strep. mutans. All Strep. sobrinus isola tes produced GTF-I of Strep. sobrinus. The Strep. mutans GTF-I, GTF-SI and GTF-S production of isolates exhibiting a different ribotype show ed variability. The variability of GTF-SI and GTF-S production was les s pronounced for serotype e isolates. The GTF-I production by Strep. s obrinus isolates did nor vary. Transmitted strains produced the same l evels of GTFs as strains that were distinct (not transmitted). Strep. mutans isolates of caries-active children produced the same levels of GTF-I and GTF-S, but tended to produce lower levels of GTF-SI than iso lates of caries-free children. In conclusion, the results suggested th at Strep. mutans isolates exhibiting a different ribotype often had di fferences in production of GTFs. However, no clear superiority of the high-producer over the low-producer strains was found in regard to the ir colonization or caries promotion in young children. (C) 1997 Elsevi er Science Ltd.