Antigenic relationships between the enteroinvasive Escherichia coli O antigens O28ac, O112ac, O124, O136, O143, O144, O152, and O164 and Shigella O antigens.

Enteroinvasive Escherichia coli strains have been found in the following O serogroups: O28ac, O112ac, O124, O136, O143, O144, O152, and O164. The biochemical reactions of these enteroinvasive E. coli strains are often similar to those of Shigella strains, and identification may be difficult. The problem of differentiation and identification is further complicated by the sharing of antigenic components. The antigenic relationships between these O antigens and those of all the established and provisional Shigella serovars were examined. O antigen identity was demonstrated between E. coli O124 and Shigella dysenteriae 3 and between E. coli O152 and provisional Shigella serovar 3341:55. Reciprocal relationships were found between E. coli O112ac and S. dysenteriae 2, S. boydii 1, S. boydii 15, between E. coli O136 and S. dysenteriae 3, and between E. coli O164 and S. dysenteriae 3. A one-way relationship was demonstrated between E. coli O136 and S. boydii 1. The remaining enteroinvasive E. coli O serogroups showed no significant antigenic relationships with any Shigella serovar.