Year of Graduation


Document Type




Directing Professor

Dr. Mary Jane Carmichael


The oral microbiome is a complex community of microorganisms that can both reflect and greatly influence the health of the human host. A number of diseases are associated with dysbiotic oral microflora in infants and children, including dental (e.g. dental caries, gingivitis, and periodontal disease), and gastrointestinal diseases (e.g. pediatric appendicitis, celiac disease, and pediatric inflammatory bowel disease). A variety of factors can influence the composition of the oral microbial community in infants, including gestation length, mode of delivery, feeding method, and diet. This study focuses on the effects of diet on the growth of a commensal bacterium (Streptococcus mitis) and pathogenic bacterium (Streptococcus mutans) commonly found in the oral cavity of infants. A culture-dependent model was utilized to test the effects of one infant formula supplemented with a probiotic (Lactobacillus rhamnosus) (Nutramigen Enflora) and one infant formula without probiotic supplementation (Enfamil NeuroPro) on the growth of the commensal and pathogen. The growth of the commensal and pathogen were assessed by measuring colony forming units (CFUs), pH levels of culture media and by performing a Snyder’s media test (a measure of acidogenesis and pathogenicity) over time. Results indicate that the probiotic-supplemented formula may selectively inhibit the growth of the pathogen and aid in producing more favorable conditions for the commensal. The additional health benefits to the gut conferred by the probiotic 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.