Phagomagnetic separation in combination with real-time PCR assay for detection of Salmonella Enteritidis and Typhimurium in dairy products

Salmonella Enteritidis (SE) and Salmonella Typhimurium (ST) are the most commonly reported serotypes detected for the occurrence of Salmonellosis through foodborne transmission in recent years. In this study, a phagomagnetic separation in combination with qPCR (PhMS-qPCR) based on phage T102 as a recognition element was developed for rapid enrichment and detection of Salmonella in dairy products. Phage T102 was coated onto magnetic beads for capturing Salmonella from samples through magnetic separation, with a capture efficiency of ~90% demonstrated. During the subsequent qPCR process, captured Salmonella was identified by detecting the OmpC gene, and specific sdf and STM4495 genes to further distinguish the serotypes of Salmonella Enteritidis (SE) and Salmonella Typhimurium (ST), respectively. The whole procedure can be performed in 2.5 h with a low detection limit of 10 CFU/mL in PBS. Subsequently, this detection strategy was successfully applied for the detection of Salmonella and serotype identification in spiked milk samples. This cell separation and detection system offers a promising alternative for rapid and accurate detection of Salmonella or Salmonella spp.