Development of oral bacterial flora in young children.

The intimate relationship with bacteria is a fundamental factor in the health status of an individual. After birth infants are exposed to continuous person-to-person and environmental contacts with microbes, and the development of the indigenous microflora begins on the surfaces of the human body. In a developing ecosystem microbial colonization may easily occur because of the still inadequate host response. Adhesion is the initial event in the colonization of bacteria. In the mouth, only mucosal surfaces are available during the first months of life. After teeth emerge, the number of attachment sites and potential niches increases significantly. Bacteria adhere not only to oral surfaces but also to each other, forming multigeneric communities where specific partner relationships influence their composition and stability. Viridans streptococci and a strictly anaerobic species, Fusobacterium nucleatum, are of interest in this context. The oral colonization pattern differs between individuals already in infancy; variable bacterial load in saliva of attendants and other close contacts and the frequency of this bacterial exposure may partly account for individual differences. In addition, the exposure of an infant to antibiotics affects the quality of colonizing bacteria. This article presents an overview of the age-related acquisition of oral bacteria and the role of the indigenous oral microflora in health and disease.