부산대학교 도서관

The potentially low infective dose of Escherichia coliO157 makes it necessary to be able to detect low numbers in food, and the lack of sensitivitiy of direct plating has led to the development of various enrichment and detection methods. Until now, the most selective procedure for detection of E. coliO157 isolates was the immunomagnetic separation (IMS) method. The number of sorbitol non‐fermenting micro‐organisms other than E. coliO157 that adhere non‐specifically to the magnetic beads hampers the application of IMS. The use of IMS in conjunction with 3 M Petrifilm‐HECTMyielded EHEC O157 in 21 of 165 samples of minced meat (12·7%). Without advance application of IMS, Petrifilm plates often yield confluent growth and colonies too numerous to count. The Vitek Immunodiagnostic Assay SystemTM(VIDAS‐ECO) showed good sensitivity when testing artificially contaminated beef samples, but only four of 21 naturally contaminated samples were recognized. The addition of 3 M Petrifilm to IMS resulted in less growth of contaminants and eliminated much of the need to test presumed colonies for confirmation. The combination of IMS with 3 M Petrifilm‐HECTMis a fast and efficient screening procedure for E. coliO157 in minced meat.