Analysis of enterohemorrhagic Escherichia coli serotype O157 : H7 by flow cytometry using monoclonal antibodies

To develop a rapid and specific method to detect and/or identify enterohemo rrhagic Escherichia coli O157:H7, two mouse monoclonal antibodies (MAbs) we re prepared. Specificities of these two MAbs (1D9 and 3E8) were determined by now cytometry method (FCM). MAbs 3E8 and 1D9 were found to react with E. coli O157:H7, Citrobacter freundii and Salmonella group N (O:30), but not with Escherichia hermannii. With a mixture containing strains of E. coli O1 57:H7 and E. coli O6:H1, two different peaks appeared in FCM with MAbs, whe reas a single peak appeared with polyclonal rabbit antiserum. From these fi ndings, FCM with MAb is suggested to be a rapid, specific, and useful metho d to detect and identify strain(s) of E. coli O157:H7 in food ingredients.