Immunochemical Studies on <em>Citrobacter</em> O Antigens (Lipopolysaccharides).

An investigation on the sugar compositions of lipopolysaccharides (O antigens) derived from 45 well—defined Citrobacter serotypes was carried out. As a result, a chemical classification into 20 chemotypes was achieved, of which 11 were identical with chemotypes occurring in Salmonella and Escherichia coli. All Citrobacter lipopolysaccharides contained glucosamine, glucose, heptose, 2-keto-3-deoxyoctonate and galactose, the latter, in some cases, in very small amounts. These sugars probably represent building blocks of the basal core polysaccharides, whose structures however may not be identical for all Citrobacter lipopolysaccharides. In addition to the basal sugars, the following monosaccharides were detected as constituents of the various Citrobacter lipopolysaccharides; D-xylose, D-mannose, fucose, rhamnose, 6-deoxylatose, 4-deoxy-D-idose, abequose, galactosamine, D-fucosamine, 3-amino-3,6-dideoxy-glucose and -galactose. The sugar compositions of serologically related Citrobacter and Salmonella O antigens were compared. While some cross-reacting pairs belonged to the same chemotype, other proved to be distinct with respect to their sugar constituents. [ABSTRACT FROM AUTHOR]