Structural and serological characterisation of the O-specific polysaccharide of the lipopolysaccharide from proposed new serotype 029 of Serratia marcescens

Abstract

The structure of the repeating unit of the O-antigenic polysaccharide from the lipopolysaccharide (LPS) of Serratia marcescens strain 111 was determined by compositional and methylation analyses and NMR spectroscopy as →6)-α-D-Glc p-(1→2)-α-L-Rha p-(1→2)-α-L-Rha p-(1→2)-α-L-Rha p-(1→ (Rha, rhamnose) which represents a new O-antigenic structure in LPS of S. marcescens but is similar to the structure of the repeating unit of the O-antigen of S. marcescens 018 →6)-α-D-Glc pNAc-(1→2)-α-L-Rha p-(1→2)-α-L-Rha p-(1→2)-α-L-Rha p-(1→ (Oxley D., Wilkinson S.G. Structure of a neutral polymer isolated from the lipopolysaccharide of the reference strain for S. marcescens serogroup 018. Carbohydr Res 1989; 195: 111-115). Serological investigations using S. marcescens O- and K-specific ELISA tests and immunoblotting showed that S111 reacted with anti-O18 and anti-K4 sera, and that the anti-S111 serum reacted with serotype strain 018. The K4 reaction was confirmed as capsular by the Quellung reaction. After absorption with the heterologous strain, S. marcescens 018 and strain 111 were shown to be immunologically distinct, probably because of the presence of the GlcNAc residue in 018. We propose to add S111 to the O-serotype strains of S. marcescens as 029.