Comparative Evaluation of a Novel Phage Protein Ligand Assay and Immunomagnetic Separation Method To Isolate the Seven Top Serogroups of Escherichia coli (O157, O26, O103, O145, O111, O45, and O121) in Foods at Risk

Abstract

ABSTRACT The presence of Shiga toxin–producing Escherichia coli (STEC) in food is a major concern for food safety authorities and industries. Methods for detecting these pathogenic bacteria are crucial. Enrichment of foods for STEC identification has been optimized, but selective concentration of bacteria before isolation still needs to be improved. In the present study, we tested the performance of the VIDAS ESPT detection method against that of the immunomagnetic separation (IMS) method. A preenrichment inoculation was performed to provide a realistic scenario of the contamination that occurs in foods, and the methods were then compared. Results obtained were then confirmed in naturally contaminated foods. Preenrichment inoculation assays revealed that the novel concentration method using phage recombinant proteins or the selective capture of the target top seven STEC serogroups is as specific and sensitive as IMS. Subsequent evaluation of naturally contaminated samples confirmed that the novel concentration method and IMS are equivalent in performance under the conditions tested.