Polymerase Chain Reaction(PCR) Method for Detection of Salmonella in Foods

To establish a rapid detection technique for Salmonella in foods by polymerase chain reaction(PCR). Amplification of nucleotide sequences within the invA gene of Salmonella was evaluated as a means of detecting Salmonella. A collection of 77 strains of Salmonella, isolated mostly from humans and animals in China, and a collection of 24 genera of non-Salmonella bacteria were used for the research of detecting Salmonella in foods by the PCR. Results: (1) The PCR method of detecting Salmonella was established, including sample preparation, amplification of Salmonella, DNA extraction, amplification of the DNA and detection of the amplification products. The result showed that the PCR method had good stability because the Mg ++ and the annealing temperature had little impact on the PCR reaction. (2) All the Salmonella strains could be amplified into 284 bp products while none of the non-Salmonella genera yielded specific amplification product. (3) The assay allowed detection of Salmonella from foods containing 102 CFU/g of the bacteria within 19 hours. In contrast to the conventional culture technique, the PCR method is more rapid, sensitive and specific. (4) The assay was able to detect Salmonella from a lot of food at the same time in a shorter period. The method deserves spreading. A rapid, sensitive and specific PCR method is established to detect Salmonella in foods.