Comparison of three real-time PCR-based methods for the detection of Listeria monocytogenes in food
2007
Oravcová, K.,Food Research Institute, Bratislava (Slovak Republic) | Trnčíková, T.,Food Research Institute, Bratislava (Slovak Republic) | Kaclíková, E.,Food Research Institute, Bratislava (Slovak Republic)
Three PCR-based methods for the detection of Listeria monocytogenes in food were compared, using EN ISO 11290-1 as the reference method. All methods tested involved culture enrichment followed by the real-time PCR identification and produced final results on the next day after sample collection. Forty selected food samples, artificially contaminated with L. monocytogenes, and seven naturally contaminated samples were analysed using TaqMan Listeria monocytogenes Detection Kit (Applied Biosystems), iQ-Check Listeria monocytogenes Kit (Bio-Rad) and an in-house method, consisting of a two-step selective enrichment followed by duplex real-time PCR employing a TaqMan probe. Using the TaqMan detection kit, the detection limits of the methods for artificially contaminated samples were 10 CFU per sample with the exception of chicken and pork liver, and for naturally contaminated raw meat products. With both kits utilizing a single-step enrichment, PCR inhibition was observed with artificially contaminated food matrices containing chocolate. Our in-house real-time PCR-based method produced positive results with all samples. Detection limits for dead L. monocytogenes cells were 10E6 CFU per sample for the in-house method and 10E3–10E4 CFU per sample for commercial kits. Real-time PCR-based methods proved to be powerful tools for fast, sensitive and accurate L. monocytogenes detection in food. If the price of analysis is a decisive factor, our in-house method is the method of choice.
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