The relationship between bottle usage/content, age, and number of teeth with Mutans Streptococci colonization in 6-24-month-old children

Objectives: Mutans streptococci (MS) are the primary pathogens involved in the development of early childhood caries. However, factors that may affect their acquisition in the mouths of young children are not well understood, and the period of initial colonization remains controversial. This study investigated the relationship of age, number of teeth, and bottle usage/content with regard to the isolation of MS in 6-24-month-old children. Methods: A total of 122 children from low-income families attending a nutritional supplement program, and their mothers, participated in this study. Children were examined for dental caries and number of erupted teeth and were sampled for MS. Mothers were administered a questionnaire to obtain details of baby bottle use, including what food items were put in the bottle during the last week. Results: MS was detected in more than one-third of the 6-24-month-olds. Unlike some studies that suggest a later period of infectivity, approximately 20% of children under 14 months of age, including 4 of 22 infants aged 6-9 months, were colonized with MS. When examined separately, age, number of teeth, and bottle usage/content were each found to be related to the presence of MS. Mutans streptococci colonization was more likely with increasing age and number of teeth, and children whose bottles contained sweetened beverages were more likely to be colonized than children whose bottles contained milk. Logistic regression models that controlled for both age and number of teeth indicated that children who consumed sweetened beverages in their baby bottle had a statistically significant, four-fold increase in the odds of colonization by MS relative to children who consumed milk. Conclusions: The finding that approximately 20% of the children under 14 months of age were infected with MS indicates that colonization in this sample of low-income preschool children may begin earlier than suggested by some investigations. Additionally, the risk of MS colonization appears lower among infants who consume milk rather than sweetened beverages in the bottle.