Vertical transmission of MS from mother to infant is well
documented.41-44 Genotypes of MS in infants appear identical
to those present in mothers in 17 reports, ranging from 24
to 100 percent.43 The higher the levels of maternal salivary
MS, the greater the risk of the infant being colonized.45-47
The success of transmission and resulting colonization of the
mother’s salivary MS may be related to several factors
including the magnitude of the inoculum, frequency of
inoculation, and a minimum infective dose.48-50 Along with
maternal salivary levels of MS, the mother’s oral hygiene,
periodontal disease, snack frequency, and socioeconomic
status also are associated with infant colonization.40 Reports
indicate that horizontal transmission (ie, transmission between
members of a group such as siblings of a similar age or
children in a daycare center) occurs.51-54 A study of children
with severe early childhood caries (S-ECC) revealed that nonmaternal
MS genotypes were identified in the majority (74
percent) of children.