• Citrobacter;
  • Salmonella;
  • Pseudomonas aeruginosa;
  • Immunospecificity;
  • Lipopolysaccharide;
  • O-Specific polysaccharide;
  • Structure;
  • O-Acetyl group

Abstract Structural analysis using 13C NMR spectroscopy and methylation showed that lipopolysaccharides (LPSs) of Citrobacter freundii O35 and Salmonella arizonae O59 have structurally identical O-specific polysaccharide chains, and those of C. freundii O38 and Salmonella kentucky differ only in the presence of O-acetyl groups in the former. Serological relationships between the structurally similar LPSs were demonstrated using inhibition of ELISA, rocket immunoelectrophoresis, double gel diffusion, and immunoblotting. The O-acetyl groups present in C. freundii O38 LPS are of little importance for its serological specificity. A cross-reaction was observed in immunoblotting between O-antisera to C. freundii O35 and S. arizonae O59 and a structurally related LPS of Pseudomonas aeruginosa O11a,11b (Lányi-Bergan classification).