Detection of heat-labile enterotoxin-producing escherichia coli strians by a staphylococcal coagglutination technique

Abstract

Culture filtrates of 50 strains of Escherichia coli isolated from children with diarrhoea were tested for heat-labile enterotoxin (LT). by the staphylococcal coagglutination technique in a slide and capillary tube. The results were compared with those obtained in bio-assays of rabbit ileal-loop and skin permeability factor. Coagglutination in a capillary tube was found to be far superior to that on a slide; and the technique detected LT in 38 of the culture filtrates. The results obtained in capillary tube coagglutination were identical to those observed in a skin permeability factor assay. The ileal-loop test detected LT in 36 of the culture filtrates and ST in 5. results which were confirmed by suckling mice assay. Thus, the staphylococcal coagglutination test is as sensitive and specific as are bio-assays. This test, being very simple and inexpensive, can be used in routine diagnostic laboratories, to assess the role of LT-producing £. coli strains in diarrhoeal diseases