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

Abstract

Aims: To evaluate the LightCycler Salmonella Detection Kit and the TaqMan^®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 × 10³ 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.