Detection of Verocytotoxin-Producing Escherichia coli O157 by Polymerase Chain Reaction Assay After Immunomagnetic Separation-Plating

Abstract

For detection of verocytotoxin-producing Escherichia coil (VTEC) O157 in foods and feces, colony isolation on selective agar after immunomagnetic separation (IMS) was followed by polymerase chain reaction (PCR) assay. It was shown that Rainbow agar O157 could recover E. coli O157 more sensitively than other selective media such as Desoxycholate agar, DHL agar, SIB agar, CT-SMAC agar, BCM O157, Chrom agar O157 and Chrom agar E. coli. Also, the PCR assay of the typical colonies developed on Rainbow agar O157 was able to detect VTEC O157 in sample suspensions with more than 10¹ cfu/ml.