Comparative Evaluation of RTi-PCR and Mini-VIDAS SLM System as Predictive Tools for the Routine Detection of Salmonella spp. in Naturally Contaminated Food Products

In the present work, we have evaluated a real-time polymerase chain reaction-based method (RTi-PCR) as a routine laboratory test, by comparing the results obtained in two laboratories with the mini-VIDAS SLM (bioM,rieux), a standard accepted immunoenzymatic (enzyme-linked immunosorbent assay) method currently used in the food industry. To that aim, a set of 141 naturally contaminated food samples were analyzed after an enrichment step by conventional PCR and mini-VIDAS and prior to the enrichment by RTi-PCR. Results from both laboratories were statistically analyzed using the kappa coefficients, which indicated a perfect agreement between them. Out of the 141 samples, 11 were positive for Salmonella detection by mini-VIDAS, 35 by conventional PCR in Lab1, and 44 in Lab2. Twenty-eight of them tested positive by RTi-PCR in Lab1 and 31 in Lab2. In order to use the evaluated methods as a diagnostic test, their predictive capacity was analyzed on the basis of their positive and negative predictive values, calculated using the result obtained-after enrichment-by conventional PCR as the "gold standard." Both positive and negative predictive values were higher for RTi-PCR than those obtained for mini-VIDAS, indicating good performance of the RTi-PCR technique-applied without enrichment-in the detection of Salmonella in food products. Overall, results obtained in this study on naturally contaminated food products highlighted that RTi-PCR without enrichment is a better predictive tool than mini-VIDAS.