Immunoelectrophoretic patterns of extracts from all escherichia coli o and k antigen test strains correlation with pathogenicity

Simple water extracts of all Escherichia coli O antigen test strains 01–0150 and K antigen test strains K1–K91 were examined in immunoelectrophoresis test. The precipitation arcs corresponding to the O antigen specificity and to the thermostable polysaccharide K antigen were easy to identify. All strains gave an O antigen precipitation arc found either on the anodic or the kathodic side of the application basin, and close to this. Only a limited number of strains contained a special thermostable K polysaccharide, always negatively charged. According to the movement of the O antigen and to presence or non-presence of a polysaccharide K antigen, the extracts and thus the strains could be divided into a few groups which fitted well with our present knowledge about pathogenicity in different E. coli strains. Serotypes found frequently in normal faeces and in extra intestinal disease had kathodic O antigens and a special negatively charged K antigen. The so-called enteropathogenic types (from infantile diarrhoea) had a kathodic O antigen and no special K antigen. Types from dysentery-like disease had a negatively charged O antigen but no special thermostable K antigen. Thus E. coli strains which may invade the tissues when conditions allow have a negatively charged surface antigen, either O antigen lipo-polysaccharide or K antigen polysaccharide or both. Acidic components, most often hexuronic acids or neuramic acid, were found in side chains from most of the strains with an anodic O antigen.