Development of a Multiplex Recombinase Polymerase Amplification Coupled with Lateral Flow Dipsticks for the Simultaneous Rapid Detection of Salmonella spp., Salmonella Typhimurium and Salmonella Enteritidis

Salmonella spp. is one of the world-leading foodborne pathogens and its rapid detection is essential to ensure food safety. In this study, a visual method was established based on multiple recombinase polymerase amplification (RPA) coupled with lateral flow dipsticks (LFD) for the simultaneous detection of Salmonella spp., Salmonella Enteritidis (S. Enteritidis) and Salmonella Typhimurium (S. Typhimurium). The optimal volume and temperature for the multiplex RPA-LFD method were optimized as 25 μL and 38℃, respectively. The reaction process was completed within 25 min and the detection results were observed visually. The limit of detection (LOD) was 2.8×102, 5.9×102 and 7.6×102 CFU/mL for Salmonella spp., S. Enteritidis and S. Typhimurium, respectively. Meanwhile, the detection results of the established method showed no cross-reactivity between object Salmonella cells and other common foodborne bacteria, which was highly specific for Salmonella. More importantly, the developed method exhibited good performance in artificially contaminated chicken samples, and the LOD in artificially contaminated chicken samples was 2.8×103, 5.9×103 and 7.6×103 CFU/mL for Salmonella spp., S. Enteritidis and S. Typhimurium, respectively. Finally, the application of the multiple RPA-LFD method in retailed food samples displayed that this method was effectively and practically in the detection of Salmonella spp., S. Enteritidis and S. Typhimurium food. This multiplex RPA-LFD method provides a new sensitive and rapid alternative for the specific detection of Salmonella spp. and its important serovars in food.