The Influence of Infant Formulae on the Growth of Commensal and Pathogenic Streptococcus Species in the Infant Oral Cavity

Abstract

The oral microbiome is a complex community of microorganisms that influences the health of the human host. A number of diseases are associated with dysbiotic oral microflora in infants and children, including dental and gastrointestinal diseases. A variety of factors can influence the composition of the oral microbial community in infants, including mode of delivery, feeding method, and diet. This study focuses on the effect of nutritional differences in infant formulae on the growth of a commensal species (Streptococcus mitis) and a pathogenic species (Streptococcus mutans) that are commonly found in the infant oral cavity. A culture-dependent model was utilized to test the effects of one infant formula (Nutramigen Enflora) supplemented with a probiotic (Lactobacillus rhamnosus) and a similar infant formula without probiotic supplementation (Enfamil NeuroPro) on the growth of each species. A Snyder’s media test was used to assess acidogenic potential of each species. Bacterial growth in each formula was assessed by measuring colony forming units (CFUs) and by measuring the pH of the culture media over an 8 hour incubation. Results indicate that the probiotic formula may selectively inhibit the growth of the pathogen and aid in producing more favorable conditions for the commensal. These findings may make Nutramigen Enflora the preferred infant formula for overall health. The results of this study may assist parents in selecting alternatives to breastmilk that will support the proper development of the infant oral microbiome by favoring the growth of commensal bacteria.