Structure of the O-polysaccharide isolated from Cronobacter sakazakii 767

Abstract The Cronobacter spp., previously known as Enterobacter sakazakii , are Gram-negative enterobacterial pathogens that can cause necrotizing enterocolitis, meningitis, and septicemia with a high mortality rate in neonates. The O-specific polysaccharide (O-PS) was isolated from Cronobacter sakazakii strain 767 and structurally characterized using 1 H and 13 C NMR spectroscopy, including two-dimensional DQF-COSY, TOCSY, ROESY, HSQC, and HMBC experiments. Further compositional determination was undertaken using classical chemical methods followed by GLC, and GLC–MS analysis. The repeating unit of O-PS isolated from C. sakazakii 767 was a branched heptasaccharide composed of l -Rha, d -Glc, d -GlcNAc, and d -GalA, and had the structure shown below. One of the Rha residues was partially O-acetylated at C-4. C. sakazakii 767 was originally isolated from a fatal neonatal meningitic case, and the structure of its O-PS significantly differs from the O-PS structures previously described for Cronobacter spp. Download full-size image