Comparison of Culture, Conventional and Real-time PCR Methods for Listeria monocytogenes in Foods

다국어 초록 (Multilingual Abstract)

We compared standard culture methods as well as conventional PCR and real-time PCR for the detection of Listeriamonocytogenes (L. monocytogenes) in milk, cheese, fresh-cut vegetables, and raw beef that have different levels of back-ground microflora. No statistical differences were observed in sensitivity between the two selective media in all foods. Intotal, real-time PCR assay exhibited statistically excellent detection sensitivity (p<0.05) and was less time consuming andlaborious as compared with standard culture methods. Conventional culture methods showed poor performance in detectingL. monocytogenes in food with high levels of background microflora, generating numerous false negative results. While thedetection of L. monocytogenes in fresh cut vegetable by culture methods was hindered only by L. innocua, various back-ground microflora, such as L. innocua, L. welshimeri, L. grayi, and Enterococcus faecalis appeared on the two selectivemedia as presumptive positive colonies in raw beef indicating the necessity of improvement of current selective media. Itappears that real-time PCR is an effective and sensitive presumptive screening tool for L. monocytogenes in various typesof foods, especially foods samples with high levels of background microflora, thus complementing standard culture meth-odologies.

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