Adherence inhibition of enteropathogenic Escherichia coli by chitooligosaccharides with specific degrees of acetylation and polymerization.

Some oligosaccharides are known to act as molecular decoys by inhibiting pathogen adherence to epithelial cells. The present study was aimed at analyzing whether chitooligosaccharides (CHOS), that is, oligomers of D-glucosamine and N-acetyl-D-glucosamine, have such antiadherence activity. CHOS of varied degree of polymerization (DP) and fraction of acetylation (F(A)) were produced. Adherence of enteropathogenic Escherichia coli (EPEC) to the surface of a human HEp-2 cell line was determined in the absence or presence of the various CHOS fractions. Adherence was assessed by microscopic counting and image analysis of bacterial clusters and cells. The results showed that all CHOS fractions inhibited adherence of EPEC to HEp-2 cells. Hydrolysates with lower F(A) were more effective at reducing adherence. This effect is greater than that obtained with other oligosaccharides, such as galactooligosaccharides, applied at the same concentrations.