Detection of Salmonella enteritidis and Salmonella typhimurium in foods using a rapid, multiplex real-time recombinase polymerase amplification assay

Salmonella has been recognized as a major foodborne pathogen for humans and animals. In this study, a multiplex real-time recombinase polymerase amplification (RPA) was developed for simultaneous detection of Salmonella enterica serovars, Salmonella enteritidis and Salmonella typhimurium, from chicken, eggs, lettuce, and papaya. The reaction was performed for 20 min at 35 degrees C, and the detection limit of the assay was 10(2) CFU/ml for pure culture. In food application, the limit of detection (LOD) of S. enteritidis and S. typhimurium using multiplex real-time RPA without enrichment procedure was 10(2) CFU/25 g, respectively. After enrichment, the LOD of S. enteritidis and S. typhimurium was 10 CFU/25 g. Moreover, the result for Salmonella spp. was not significantly different from those obtained using a culture-based method. Additionally, the assay has a lower cross-reactivity with other pathogenic microorganisms and a good stability performance. Thus, the developed multiplex RPA assay could be used as a rapid tool for the detection of S. enteritidis and S. typhimurium in food.