Evaluation of two real-time polymerase chain reaction pathogen detection kits for Salmonella spp. in food

Aims: To evaluate the LightCycler Salmonella Detection Kit and the TaqMan((R))Salmonella Gold Detection and Quantitation Kit for the real-time PCR detection of Salmonella in various food samples. Methods and Results: Ready-to-eat foods and raw food samples were artificially contaminated with Salmonella serotypes. In the specificity test, bacterial DNA extracted from sample pre-enrichment culture was analysed with the detection kits performed respectively on the LightCycler Instrument or the ABI Prism 7000 Sequence Detection System. No false-positive or false-negative results were obtained, although the LightCycler system generated invalid PCR results on two occasions. In the sensitivity test using the LightCycler system, Salmonella could be detected in pre-enrichment cultures of 25-g samples inoculated with as low as 1.5 x 10(3) CFU (depending on food type), and false-negative results were obtained for samples with low inoculum levels. Conclusions: Two commercial kits for real-time PCR detection of Salmonella were evaluated. Significance and Impact of the Study: Evaluation using more food types and matrices, and foods that contain low number of Salmonella or high number of other competing bacteria, is needed before adopting the real-time PCR technique for routine food tests.