Center for Food Safety and Applied Nutrition, U.S. Food and Drug Administration, 5100 Paint Branch Parkway, College Park, MD 20740, USA.
Foodborne Pathog Dis. 2011 Oct;8(10):1063-9. doi: 10.1089/fpd.2010.0820. Epub 2011 May 25.
Listeria monocytogenes is an intracellular foodborne pathogen that has been associated with severe human illnesses. Various rapid detection methods have been developed for the specific detection of this pathogen. In the present study, a real-time quantitative polymerase chain reaction (PCR) assay targeting iap, a gene encoding extracellular protein p60, was developed for L. monocytogenes. The PCR efficiency is above 85% and the limit of detection (LOD) is 30 copies of genome per reaction for all strains tested. The assay exhibited 100% inclusivity and exclusivity rates. The detection of L. monocytogenes in five food matrices, whole milk, soft cheese, turkey deli meat, smoked salmon, and alfalfa sprouts, was evaluated with and without enrichment. Without enrichment, the LOD for all food matrices were 4×10(3) CFU/mL food enrichment mix for whole milk and 4×10(4) CFU/mL for all other foods. With 24 h incubation in Buffered Listeria Enrichment Broth, the LOD was 3 CFU/25 g food for whole milk, turkey deli meat, and smoked salmon and 9 CFU/25 g food for soft cheese and alfalfa sprouts. With 48 h incubation, the LOD was 3 CFU/25 g food for all matrices. This quantitative PCR appears to be a promising alternative for rapid detection of L. monocytogenes in select foods.
李斯特菌是一种食源性致病菌，与人类严重疾病有关。已经开发了各种快速检测方法来专门检测这种病原体。在本研究中，针对编码细胞外蛋白 p60 的基因iap 开发了一种用于李斯特菌的实时定量聚合酶链反应 (PCR) 检测方法。PCR 效率高于 85%，所有测试菌株的检测限 (LOD) 为每个反应 30 个基因组拷贝。该检测方法具有 100%包容性和排他性。使用和不使用富集方法评估了该实时定量 PCR 检测方法对五种食品基质（全脂牛奶、软奶酪、火鸡熟食肉、熏三文鱼和苜蓿芽）中李斯特菌的检测能力。不进行富集时，所有食品基质的检测限均为每 4×10(3)CFU/mL 食品富集混合物（全脂牛奶）和每 4×10(4)CFU/mL 其他食品。在缓冲李斯特菌增菌肉汤中孵育 24 小时后，全脂牛奶、火鸡熟食肉和熏三文鱼的检测限为 3 CFU/25 g 食品，软奶酪和苜蓿芽的检测限为 9 CFU/25 g 食品。孵育 48 小时后，所有基质的检测限均为 3 CFU/25 g 食品。这种实时定量 PCR 似乎是一种很有前途的替代方法，可用于快速检测选定食品中的李斯特菌。
