The Comparison of Effect of Human Milk and Powdered Milk on the Shigella dysenteriae Invasion in Cell Culture

Abstract

Background: Shigella species are the common etiologic agents of bacterial dysentery. Many epidemiological studies have shown that breastfeeding may protect infants against intestinal infections. Among the components of milk, glycosylated proteins inhibit the adhesion of enteric pathogens in the laboratory. Immunoglobulins mainly secretory immunoglobulin A, glycosylated compounds, and oligosaccharides of breast milk are associated with protection against different intestinal pathogens. Objectives: This study aimed to evaluate the effect of different proteins of breast milk and powdered milk on the invasion of Shigella colonies. Materials and Methods: To accomplish this goal, breast milk samples were provided from two donors in the first 6 months of breastfeeding and powdered milk with different brands were obtained from the market. Then the proteins were extracted by precipitation using ammonium sulfate and dialysis using dialysis bag and protein bands were separated through SDS-PAGE electrophoresis. Finally, the obtained milk proteins through Hela cells culture were tested and evaluated for the adhesion and invasion of the Shigella. Results: Our results revealed that the adhesion and invasion of Shigella stains were more inhibited by low concentrations of breast milk proteins in comparison with powdered milk. This concentration was about 2.75 mg/mL for the proteins of breast milk and 0.5 mg/mL for the proteins of powdered milk and this inhibition in different dilutions of breast milk was 71.21% and those of powdered milk was 27.19% in average. There was a significant difference between breast milk and powdered milk (P < 0.5) considering their inhibitory behavior. Conclusion: The results revealed that the components of breast milk inhibit the adhesion and consequently invasion of Shigella and inhibit bacterial dysentery.