Improved detection of infection by Escherichia coli O157 in patients with haemolytic uraemic syndrome by means of IgA antibodies to lipopolysaccharide.

Samples of serum from 125 patients with haemolytic uraemic syndrome, were screened for antibodies of the IgA and IgM classes to the lipopolysaccharide (LPS) of Escherichia coli O157:H7. By means of the techniques of ELISA and immunoblotting, 48 samples were shown to contain antibodies of the IgM class to E. coli O157 LPS, while 42 samples contained IgA antibodies to this O-antigen. Thirteen patients produced IgM but not IgA antibodies to the LPS of E. coli O157:H7. Of 42 patients with IgA antibodies to the E. coli O157 LPS, seven did not produce antibodies of the IgM class. From this study, screening patients' serum for antibodies to E. coli O157 LPS of the IgA class, in addition to those of the IgM class, a total of 55 patients were shown to be seropositive. This constituted an increase is in the sensitivity of obtaining evidence of infection by this organism by 12%.