In vitro evaluation of milk-based, soy-based, and amino acid-based infant formulas on Streptococcus mutans biofilm formation

Abstract

Background and Objective: Infant formulas are based on milk, and the addition of simple carbohydrates as a caloric source, for infants. The carbohydrates added in infant formulas can cause a significant increase of Streptococcus mutans in the oral cavity of infants adding to their cariogenicity. Aim: The aim of the study was to assess and compare the biofilm formation in three commercially available infant formulas;which are based on milk, soy and amino acid. Settings and Design: In vitro microbiological assay of Streptococcus mutans biofilm formation in milk based, soy based and amino acid based infant formulas. Materials and Methods: Twenty-four hour-cultured S. mutans and microtiter plates were used for analysis. At microtiter plate, 190 μL of modified TSB broth containing SBF, MBF, amino acid-based infant formulas, and dairy whitener as a positive control in five dilutions (1:05, 1:10, 1:20, 1:40, and 1:80) was added into respective wells. 10 μL of cultured S. mutans was inoculated into the wells and incubated at 37°C for 24 h. Biofilm was washed, fixed, and stained with crystal violet. The absorbance was measured to evaluate biofilm growth, which was read as optical densities in a spectrophotometer at 490 nm and was tabulated. Results: Three infant formulas tested showed S. mutans biofilm growth. Minimal biofilm growth was observed in amino acid-based formula at 1:80 dilution, followed by MBF at 1:10 dilution and SBF at 1:80 dilution. Conclusion: Commercially available infant formulas favor S. mutans biofilm growth and can be cariogenic. Amino acid-based infant formula was found to have less S. mutans biofilm growth than MBF and SBF.

Keywords

• biofilm
• dental caries
• infant formulas
• streptococcus mutans