Evaluation of a Multiplex PCR Assay for the Identification of Salmonella Serovars Enteritidis and Typhimurium Using Retail and Abattoir Samples

ABSTRACT A multiplex PCR was developed to identify the two most common serovars of Salmonella causing foodborne illness in Canada, namely, serovars Enteritidis and Typhimurium. The PCR was designed to amplify DNA fragments from four Salmonella genes, namely, invA gene (211-bp fragment), iroB gene (309-bp fragment), Typhimurium STM 4497 (523-bp fragment), and Enteritidis SE147228 (612-bp fragment). In addition, a 1,026-bp ribosomal DNA (rDNA) fragment universally present in bacterial species was included in the assay as an internal control fragment. The detection rate of the PCR was 100% among Salmonella Enteritidis (n = 92) and Salmonella Typhimurium (n = 33) isolates. All tested Salmonella isolates (n = 194) were successfully identified based on the amplification of at least one Salmonella-specific DNA fragment. None of the four Salmonella DNA amplicons were detected in any of the non-Salmonella isolates (n = 126), indicating an exclusivity rate of 100%. When applied to crude extracts of 2,001 field isol...