Evaluation of an Automated ELISA (VIDAS®) and Real-time PCR by Comparing with a Conventional Culture Method for the Detection of Salmonella spp. in Steamed Pork and Raw Broccoli Sprouts

Salmonellosis is an important worldwide foodborne infectious disease that is transmitted by many food vehicles including raw and processed animal products and fresh produce. In this study, the effectiveness of automated ELISA (VIDAS (R)) and real-time PCR in the detection of Salmonella spp. in steamed pork and raw broccoli sprouts was evaluated by comparing their results with those of a conventional culture method. Bulk samples (500 g) of steamed pork and raw broccoli sprouts were inoculated with various levels of Salmonella and divided into 20 samples (25 g each). All the samples, including the controls, were analyzed using a conventional culture method, VIDAS (R), and real-time PCR to detect the presence of Salmonella. In addition, the levels of background flora in the steamed pork and the raw broccoli sprouts were determined. In the steamed pork that contained less than 100 CFU/g of aerobic bacteria, all three methods detected low levels of Salmonella without a statistical difference in their performance. In the broccoli sprouts with high quantities of background flora (ca. 6.7x10(7) CFU/g), however, all three methods were unable to detect low levels of Salmonella, and real-time PCR and VIDAS (R) more sensitively detected Salmonella than the culture method, with significant statistical differences. In conclusion, VIDAS (R) and real-time PCR could be superior to conventional culture methods in detecting Salmonella in food with high levels of background flora.