Rapid multiplex PCR and real-time TaqMan PCR assays for detection of Salmonella enterica and the highly virulent serovars Choleraesuis and Paratyphi C

Salmonella enterica is a human pathogen with over 2,500 serovars characterized. S. enterica serovars Choleraesuis and Paratyphi C are two globally distributed serovars. We have developed a rapid molecular-typing method to detect serovars Choleraesuis and Paratyphi C in food samples by using a comparative-genomics approach to identify regions unique to each serovar from the sequenced genomes. A Salmonella-specific primer pair based on oriC was designed as an internal control to establish accuracy, sensitivity, and reproducibility. Serovar-specific primer sets based on regions of difference between serovars Choleraesuis and Paratyphi C were designed for real-time PCR assays. Three primer sets were used to screen a collection of over 100 Salmonella strains, and both serovars Choleraesuis and Paratyphi C gave unique amplification patterns. To develop the technique for practical use, its sensitivity for detection of Salmonella spp. in a food matrix was determined by spiking experiments. The technique was also adapted for a real-time PCR rapid-detection assay for both serovars Choleraesuis and Paratyphi C that complements the current procedures for Salmonella sp. isolation and serotyping.