Development of a Rapid Test Method for Salmonella enterica Detection Based on Fluorescence Probe-Based Recombinase Polymerase Amplification

Salmonella is a type of serious foodborne pathogenic bacterium that threatens the food safety worldwide. In this study, a fluorescence probe-based recombinase polymerase amplification analytical method (exo RPA) was developed for the sensitive and specific detection of Salmonella enterica (S. enterica). The primers and probe for this method were designed based on the iroB gene of the bacterium. The exo RPA reaction could detect as low as 102 copies of template DNA per reaction or 2.2 × 103 CFU/mL of S. enterica, and SPSS probit regression analysis indicated the limit of detection (LOD) at 95% probability of the exo RPA assay was 2.0 × 103 CFU/mL. Moreover, the exo RPA assay could successfully differentiate S. enterica from all the tested non-Salmonella strains. Importantly, this method is highly reliable; the DNA from other bacteria or food complex matrices has no obvious effect on the S. enterica exo RPA. Besides, positive signal could be obtained from the chicken or egg sample inoculated with 2.2 × 101 CFU/mL of S. enterica after 4- to 6-h enrichment at 36 °C. Therefore, this study describes a rapid test method for S. enterica, which is expected to be beneficial for monitoring trace S. enterica in real food products.