Mother-to-child transmission of Streptococcus mutans

PubMed, the Cochrane Library databases and the Virtual Health Library were searched from January 1950, with a manual search of the reference lists of the included studies.

Duplicate papers, case reports, case series, descriptive studies, review articles, opinion articles and letters were excluded along with studies on children with oral defects, and ongoing preventative/restorative treatment and mothers who used antimicrobial substances. Two authors independently screened the title and abstract of all identified records, with consensus if required by a third author. A PECO (E= exposure) strategy was used to assess the eligibility of identified papers: observational human studies whose subjects were mother and child pairs; P contaminated by S.mutans; E comparison according to the presence and absence of S.mutans; C and whether there is vertical transmission (as defined by molecular analyses); O.

Included studies were assessed for risk of bias. Two researchers extracted data on the methods, participants and outcomes, and the authors were contacted when it was necessary to clarify details. The percentage of transmission before and after the year 2000 was evaluated using the t-test and the molecular analysis technique was evaluated using ANOVA. A cumulative meta-analysis based on the publication year was performed, combining studies that assessed mother/child bionomy (pairs) and presented the percentage of transmission.

Thirty-six cross-sectional studies were included, with the age of the children varying among the studies from three weeks to 15 years. All but one of the studies confirmed the vertical transmission of S. mutans from mother to child by genetic methods. The pooled cumulative meta-analysis demonstrated vertical transmission of S. mutans from mother to child (p<0.01) and showed a tendency of reduction in the percentage of vertical transmission compared with the year the studies were published.There was no significant difference in the transmission rate according to the type of technique used (p=0.39; ANOVA test). Quality assessment found that twenty-eight studies had bias such as confounding factors. All of the studies included were cross-sectional studies and therefore none was randomised. There were no reports of blinding in the selected studies although some studies evaluated the testing accuracy and repeatability or calibration; all included microbiological repetition.

There is scientific evidence of vertical transmission of S. mutans from mother to child as there was an association between S. mutans strains in mothers and their respective children.