A simple procedure to demonstrate the presence of the O-antigen capsule in enteropathogenic Escherichia coli.

Enteropathogenic Escherichia coli O111 bacteria very often produce a capsule-like polysaccharide exhibiting the same chemical composition as the O-specific chains of their lipopolysaccharide and being designated as O-antigen capsule. In this paper, a new simple procedure is described for the detection of this capsule polymer. O-antigen capsule polysaccharide and lipopolysaccharide of bacterial extracts were electrophoretically separated in agarose cetavlon gel, blotted onto nitrocellulose membranes and visualized by immunological methods. As a result of this procedure, the O-antigen capsule can be detected as a spot completely separated from the LPS (Figs. 1 and 2). Consequently, this method allows a clear discrimination of K+ and K- strains.