Initial acquisition and genetic identity of Streptococcus mutans of mother-child Pairs

This study's purpose was to investigate the transmission and genetic identity of Streptococcus mutans strains in mother-child pairs from Cordoba, Argentina in order to establish whether the mother was the main source of infection of the child.

Seventeen mother-child pairs were analyzed, with samples taken of whole nonstimulated saliva and dental plaque when each child was 18 months old. The mothers gave their written, informed consent to participate in the study. The Streptococcus mutans strains were genotyped by the arbitrarily primed polymerase chain reaction (AP-PCR) technique using primers OPA-02, OPA-05, and OPA-13. Three statistical analyses were used to determine genetic identity (1) Dice similarity index, (2) principal coordinates analysis/minimum spanning tree (PCoA/MST) analysis, and (3) Neighbor-joining consensus tree.

The AP-PCR technique showed high genetic polymorphism in the S mutans strains. According to the Dice index, 10 of the 17 pairs presented genetic identity. Results from the PCoA/MST analysis and the Neighbor-joining consensus tree showed that 7 pairs presented high similarity and the other 3 showed moderate levels of similarity

According to the results obtained with 3 primers and with 3 different statistical methods, we could determine that the mothers are an important source of infection for the child at an early age.