The objective of this cooperative research project is to develop a multiplex superparamagnetic fluorescent microbead immunochemical assay for foodborne pathogens in food. Specifically, the scope of this project includes simultaneous detection and identification of the seven most common strains of Shiga toxin-producing Escherichia coli (STEC) based on O antigen: O157, O26, O111, O103, O121, O45, and O145. It also includes Listeria monocytogenes serotypes 1/2a, 1/2b, and 4b; and Salmonella enterica serovar Typhimurium. Foods of interest include ground beef, liquid egg, milk, and leafy greens. Performance characteristics of the product require sensitivity of at least one infectious dose of live bacteria per serving of food.