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 enterohemorrhagic Escherichia coli O157:H7, two mouse monoclonal antibodies (MAbs) were prepared. Specificities of these two MAbs (1D9 and 3E8) were determined by flow 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 O157:H7 and E. coli O6:H1, two different peaks appeared in FCM with MAbs, whereas a single peak appeared with polyclonal rabbit antiserum. From these findings, FCM with MAb is suggested to be a rapid, specific, and useful method to detect and identify strains(s) of E. coli O157:H7 in food ingredients