Assurance enzyme immunoassay for detection of enterohemorrhagic Escherichia coli O157:H7 in selected foods: collaborative study.

Five foods types were analyzed by the Assurance EHEC (Escherichia coli O157:H7) enzyme immunoassay (EIA) and by the Bacteriological Analytical Manual (BAM) culture method. Each sample of each food type at each inoculation level was simultaneously analyzed by both methods. A total of 21 laboratories representing state and federal government agencies and private industry in the United States and Canada participated. Samples were inoculated with E. coli O157:H7, except for one lot of poultry that was naturally contaminated. A total of 1304 samples and controls were analyzed and confirmed, of which 473 were positive and 818 were negative by both methods. Thirteen samples were positive by BAM but negative by EIA. Because of the study design, it was not possible for the BAM method to produce false-negative or false-positive results. The Assurance method for detection of E. coli O157:H7 in selected foods has been adopted first action by AOAC INTERNATIONAL.