Bovine milk oligosaccharides as anti-adhesives against the respiratory tract pathogen Streptococcus pneumoniae

Abstract Streptococcus pneumoniae is a Gram-positive pathogen, which is regularly found in the upper respiratory tract of healthy individuals. Increased numbers of S . pneumoniae have been observed colonising the upper respiratory tract of children affected by respiratory tract infections. Galβ1-4GlcNAcβ1-3Gal has been previously identified as one of the receptors involved in the adherence and translocation of S .  pneumoniae . As this structure is similar to the milk oligosaccharide lacto-N-neoTetraose, many studies have investigated if free milk oligosaccharides can inhibit the adhesion of S . pneumoniae to epithelial cells of the respiratory tract. Here, we demonstrate that bovine oligosaccharides, which were extracted from demineralised whey, using a combination of membrane filtration and chromatography, were capable of reducing S . pneumoniae adhesion to pharynx and lung cells in vitro when tested at physiological concentrations. This study strengthens the potential use of bovine derived milk oligosaccharides as functional ingredients to reduce the incidence of infectious diseases.