Scientific journal

46 2007

Journal of Food and Nutrition Research
Summary No. 2 / 2007

Comparison of three real-time PCR-based methods for the detection of Listeria monocytogenes in food
Journal of Food and Nutrition Research, 46, 2007, No. 2, s. 63-67

Eva Kaclíková, Department of Microbiology and Molecular Biology, VÚP Food Research Institute, Priemyselná 4, P. O. Box 25, SK - 824 75 Bratislava 26, Slovakia. E-mail:

Summary: 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 100 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 106 CFU per sample for the in-house method and 103–104 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.

Keywords: Listeria monocytogenes; detection; real-time PCR; food

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