Twelve hour real-time PCR technique for the sensitive and specific detection of Salmonella in raw and ready-to-eat meat products.

Rapid pathogen testing is vital to the food industry. Enzyme immunoassays (EIA) provide reliable negative results in 48 h, but a presumptive positive (suspect) EIA result must be confirmed by traditional culture methods, requiring an additional 72 h. Polymerase chain reaction (PCR) testing technology is accepted as an accurate diagnostic tool. However, traditional PCR techniques can require several days. We sought to develop a rapid, real-time quantitative PCR technique for detecting Salmonella spp. in food products. Salmonella spp. was inoculated into raw and ready-to-eat beef products. Total DNA was extracted and used as template for PCR amplification in the LightCycler (Roche Diagnostics Corp., Idaho Technology Inc., Idaho Falls, ID) PCR instrument. Salmonella-specific PCR primers were designed to amplify a 251 base pair product from the junction of SipB and SipC. Fluorescently-labeled hybridization probes were designed to anneal to SipB and SipC. Salmonella was detected down to 1 colony forming unit/ml in food products. The results of real-time PCR correlated 100% to those of visual immunoprecipitate and culture. PCR methods using the LightCycler can detect and confirm the presence or absence of Salmonella spp. in raw and ready-to-eat beef products within 12 h with increased sensitivity compared to traditional culture and EIA methods.