Department of Biochemical Engineering, University of Zagreb, Croatia.
J Dairy Res. 2010 Feb;77(1):112-6. doi: 10.1017/S0022029909990379. Epub 2009 Nov 23.
Conventional methods for the identification of Listeria in foodstuffs are generally cumbersome and time consuming. The use of primary enrichment in half strength Fraser broth and the use of PALCAM agar were assessed in comparison with API Listeria and polymerase chain reaction (PCR) for their ability to accurately detect and confirm the presence of List. monocytogenes in milk products. The aim of our work was to detect List. monocytogenes in domestic unpasteurised milk, fresh cheese and cream of raw milk taken from four different district of Zagreb-Croatia using conventional (microbiological and biochemical - API test) and PCR methods. Of the 180 milk products samples tested, 27.6% were presumptively positive for Listeria on PALCAM agar. Only 21.3% of samples were confirmed to be positive for Listeria by API Listeria test, and 17.3% were confirmed to be positive for List. monocytogenes by PCR amplification of the hly gene (64 bp). PCR was able to eliminate the false positive and detect all List. monocytogenes in the milk products, unlike the conventional methods used in the industry. These results indicate a low presence of this pathogen in this area (Zagreb) of Croatia. PCR proves to be a sensitive and rapid technique to be included in the procedure of detection of List. monocytogenes in food products and this method is considerably faster than current standard methods.
传统的食品中单增李斯特菌鉴定方法通常繁琐且耗时。本研究评估了在半强化 Fraser 肉汤中进行初级富集和使用 PALCAM 琼脂，与 API 李斯特菌检测试剂盒和聚合酶链反应（PCR）相比，它们在准确检测和确认乳产品中单核细胞增生李斯特菌的存在方面的能力。我们的工作旨在使用传统（微生物学和生物化学-API 测试）和 PCR 方法检测来自克罗地亚萨格勒布四个不同地区的未巴氏消毒的国产牛奶、新鲜奶酪和生牛乳中的单增李斯特菌。在测试的 180 个牛奶产品样本中，PALCAM 琼脂上有 27.6%的样本被推测为李斯特菌阳性。只有 21.3%的样本通过 API 李斯特菌检测试剂盒被确认为李斯特菌阳性，17.3%的样本通过 hly 基因（64bp）PCR 扩增被确认为单增李斯特菌阳性。PCR 能够消除假阳性，并检测到所有乳制品中的单增李斯特菌，而不像行业中使用的常规方法。这些结果表明该病原体在克罗地亚（萨格勒布）这一地区的存在率较低。PCR 被证明是一种敏感且快速的技术，可用于食品中单增李斯特菌的检测程序，该方法比当前的标准方法快得多。
