Structure of the O-specific polysaccharide of Proteus penneri 71 and classification of cross-reactive P-penneri strains to a new proposed serogroup O64

A neutral O-specific polysaccharide (O-antigen) was isolated From the lipop olysaccharide (LPS) of the bacterium Proteus penneri 71. On the basis of su gar analysis and H-1- and C-13-NMR spectroscopic studies, including two-dim ensional COSY, C-13,H-1 heteronuclear COSY and ROESY, the following structu re of the trisaccharide repeating unit of the polysaccharide was establishe d: --> 3)-beta-D-GlcpNAc-(1 --> 4)-beta-D-GlcpNAc-(1 --> 3)-alpha-D-Galp-(1 -- > The polysaccharide has the same carbohydrate backbone as the O-specific pol ysaccharide of P. penneri 19 and both are similar to that of 19 penneri: 62 studied by us previously. A cross-reactivity of anti-P. penneri 71, 19 and 62 O-antisera with 11 P. penneri strains was revealed and substantiated at the level of the O-antigen structures. These strains could be divided into three subgroups within a new proposed Proteus O64 serogroup containing P. penneri strains only.