Characterization of the O-antigen in the lipopolysaccharide of Cronobacter (Enterobacter) malonaticus 3267

Area of Science:

• Microbiology
• Bacterial Pathogenesis
• Carbohydrate Chemistry

Background:

• Cronobacter malonaticus, formerly Enterobacter sakazakii, is a Gram-negative bacterium causing severe infections in neonates.
• Accurate identification of Cronobacter spp. is crucial for public health, necessitating detailed characterization of its antigens.
• Lipopolysaccharide (LPS) O-polysaccharide (O-PS) antigens are key targets for serological and chemical identification.

Purpose of the Study:

• To characterize the structure of the O-polysaccharide (O-PS) antigen of Cronobacter malonaticus HPB 3267.
• To provide foundational data for the development of diagnostic tools for Cronobacter identification.
• To contribute to the understanding of the antigenic determinants of this emerging pathogen.

Main Methods:

• Hydrazinolysis of lipopolysaccharide (LPS) to isolate O-polysaccharide (O-PS).
• Compositional analysis to determine the types and ratios of monosaccharide residues.
• Methylation analysis and two-dimensional high-resolution nuclear magnetic resonance (NMR) spectroscopy for detailed structural elucidation.

Main Results:

• The O-PS of Cronobacter malonaticus HPB 3267 is a polymer composed of repeating branched pentasaccharide units.
• Each pentasaccharide unit contains D-glucose, D-galactose, D-glucosamine, D-galactosamine, and Kdo residues in equimolar amounts.
• The detailed structure of the repeating oligosaccharide unit was determined.

Conclusions:

• The elucidated O-PS structure provides critical information for the serological and chemical identification of Cronobacter malonaticus.
• This structural data is essential for differentiating Cronobacter species and strains.
• The findings support the development of improved diagnostic methods for this significant opportunistic pathogen.