The EZ Coli™ Rapid Detection System consists of a selective enrichment medium and a rapid immunological detection kit. After being incubated for 15 to 24 h at 40 to 42°C, an Escherichia coli O157 culture was at a sufficient cell concentration (> 106 CFU/ml) to be tested with the EZ Coli Detection Kit. In studies of foods seeded with E. coli O157, all 42 strains of E. coli O157 tested positive with the detection kit. None of the 29 strains of E. coli non-O157 tested positive with the kit. Species of Citrobacter, Hafnia, and Klebsiella grew in the medium but tested negative. Of the 47 strains of non-E. coli O157 tested, only two strains of Salmonella 0 Group N grew and tested positive with the kit. Several laboratories evaluated the EZ Coli System with 378 clean and naturally contaminated food samples (mainly raw beef), and 337 different food samples, including raw meats (beef, pork, turkey, and chicken), dairy products, spices, vegetables, and apple cider, spiked with 50 different strains of E. coli O157 (1 to 100 CFU/25 g). Of these samples, 44.6% were positive and 52.2% were negative. The false-positive rate was 1.7% and the false-negative rate was 1.5%. The data show that high levels of coliforms (> 106 CFU/g) in food samples may impede the detection of low levels (1 to 10 CFU/25 g) of E. coli O157 organisms in broth, thereby causing false-negative reactions with most detection systems. The EZ Coli Rapid Detection System provides a rapid and specific means of detecting E. coli O157 in raw and processed foods.
Short communication: A novel method using immunomagnetic separation with a fluorescent nanobeads lateral flow assay for the rapid detection of low-concentration Escherichia coli O157:H7 in raw milk