a1 Division of Enteric Pathogens, Central Public Health Laboratory, 61 Colindale Avenue, London NW9 5HT, UK
a2 Public Health Laboratory, Leicester Royal Infirmary, Infirmary Square, Leicester LEI 5WW, UK
Sera from patients with yersiniosis. shown to contain antibodies to Yersinia enterocolitica O9; and sera from patients with haemolytic uraemic syndrome (HUS) caused by Escherichia coli O157, were used to investigate serological cross-reactions between Y. enterocolitica O9 and E. coli O157. Lipopolysaccharide (LPS) was isolated from strains of Y. enterocolitica O9 and E. coli O157 and reacted with sera by immunoblotting and ELISA. Sera from patients with HUS contained antibodies to the LPS of E. coli O157 only; 80% of sera from patients with yersiniosis contained antibodies to the LPS of Y. enterocolitica O9 and E. coli O157. This one-way cross-reaction was also detected using hyperimmune rabbit antisera.
(Accepted April 24 1991)