IDENTIFICATION OF ENTEROTOXIGENIC ESCHERICHIA COLI-PRODUCING HEAT-LABILE ENTEROTOXIN BY AN ENZYME-LINKED IMMUNOSORBENT ASSAY ON SINGLE COLONIES GROWN ON MACCONKEY AGAR PLATES

An enzyme-linked immunosorbent assay (ELISA) using one antibody has been developed to detect heat-labile enterotoxin (LT) of Escherichia coli. The ELISA was able to detect as little as 0.1 ng/mL of purified LT. This ELISA was used successfully to identify LT-producing E. coli, using single colonies grown on a selective medium, MacConkey agar. The LT amount in one colony was calculated as 0.15 to 200 ng. As results can be available within 4-5 h after obtaining colonies, this ELISA allows very rapid diagnosis of diarrhoea caused by LT-producing E. coli.