A loop-mediated isothermal amplification method targets the HisJ gene for the detection of foodborne Salmonella

A loop-mediated isothermal amplification (LAMP) assay was developed and validated for the specific detection of Salmonella in food. The four primers required for LAMP were designed using a conserved region in the histidine transport protein-coding region of Salmonella. Seventy-nine reference strains of 72 Salmonella serovars and 23 non-Salmonella strains were detected by LAMP. The detection limit of this assay is 16 CFU per reaction in pure culture, up to tenfold more sensitive than that of the PCR assay with the same target gene. When applied in raw food samples, a sample pretreatment protocol was performed that included a pre-enrichment step in 0.1 % buffered peptone water, followed by a selective enrichment in Rappaport–Vassiliadis medium. Using this method, 200 assorted food samples were investigated for Salmonella, including fresh pork, whole chickens, and green vegetables. The sensitivity of LAMP for the detection of Salmonella in food samples was 93.55 %, versus 87.10 % that tested positive using conventional PCR. The results from this study showed that the HisJ-based LAMP is an effective method for the detection of foodborne Salmonella.