Specific and rapid detection of foodborne Salmonella by loop-mediated isothermal amplification method

We developed and evaluated the specificity and sensitivity of a loop-mediated isothermal amplification (LAMP) method for rapid detection of the food-borne pathogen Salmonella. A pair of outer primers and a pair of inner primers was specially designed for recognizing six distinct sequences on the target invA gene. By the detection system, 241 bp target DNA was amplified and visualized as ladder-like pattern of bands on agarose gel within 60 min under isothermal conditions at 65 °C. The detection limit of this LAMP assay was 100 fg DNA/tube, while the PCR method was 1 pg/tube. Also, the presence of 100 ng of non-Salmonella genomic DNA in this LAMP reaction for 1 pg Salmonella of target DNA neither adversely affected the amplification efficiency nor generated significant background. In addition, the LAMP method is carried out under isothermal condition, therefore no special apparatus is needed. A regular laboratory water bath or heating block is good enough. The LAMP method reported here demonstrated a potential and valuable means for detection of Salmonella especially for its rapidity, simplicity and low cost.