A strain of Citrobacter sedlakii showing serological cross-reaction with Escherichia coli O157 antisera was demonstrated to produce a lipopolysaccharide O-antigen having an identical structure with that of the E. coli O157 O-antigen. A strain of Citrobacter freunndii showing similar cross-reaction with E. coli O157 specific monoclonal antibody was shown to produce a lipopolysaccharide O-antigen composed of a trisaccharide repeating unit having the structure [ 2)-α-D Rhap-(1-3)-β-D-Rhap-(1-4)-β-D-Glcp-(1-]. This O-antigen differs from that of the E. coli O157 O-antigen and also lacks a component 2-substituted 4-amino-4,6-dideoxy-α-D-mannopyranosyl residue implicated as the common epitope in the lipopolysaccharide O-antigens of previously investigated bacterial species showing serological cross-reactivity with E. coli O157 antisera. The C freundii O-antigen presents an interesting example of structural mimicry within a bacterial polysaccharide antigen.

Lipopolysaccharide, Escherichia coli O157:H7, antigens, O-polysaccharide, Citrobacter, Citrobacter freundii, cross-reaction

13C NMR data:
missing...
1H NMR data:
Linkage	Residue	H1	H2	H3	H4	H5	H6
4,3	aDRhap	5.14	4.22	3.87	3.44	3.86	1.27
4	bDRhap	4.70	4.10	3.68	3.46	3.45	1.30
	bDGlcp	4.50	3.36	3.64	3.63	3.53	3.85

There is only one chemically distinct structure:

SVGMWSMILES3D molIonize

 

*O[C@H]1[C@@H](O)[C@H](O)[C@@H](C)O[C@@H]1O[C@@H]1[C@H](O)[C@H](O[C@@H]2[C@@H](CO)O[C@@H](*)[C@H](O)[C@H]2O)O[C@H](C)[C@H]1O

454.425 g/mol (C₁₈H₃₀R₂O₁₃, R = next and previous repeats, not counted in mol weight)