Gilgen M, Hübner P, Höfelein C, Lüthy J, Candrian U
Department of Chemistry and Biochemistry, University of Berne.
Res Microbiol. 1998 Feb;149(2):145-54. doi: 10.1016/s0923-2508(98)80029-6.
Pathogenic strains of Escherichia coli producing verotoxins (VTs) have been recognized as a cause of human disease, and rapid and sensitive detection tests are urgently needed to ensure the safety of food, especially ground beef. We applied two nested polymerase chain reaction (PCR) assays to detect the genes encoding VT1 and VT2 irrespective of the bacterial serotype. In combination with a direct sample preparation protocol, we were able to uncover the presence of about 110 CFU of verotoxinogenic E. coli (VTEC) in 10 g of ground beef. When a six-hour enrichment was included, we found the detection limit to be in the range of 1 to 10 bacterial cells per 10 g of ground beef. To evaluate our detection system, we tested 30 ground beef samples originating from butcher shops in Berne, Switzerland. One sample yielded positive PCR results for both the VT1 and VT2 genes, indicating the presence of verotoxinogenic E. coli. Finally, 20 food homogenates, shown to contain E. coli strains by standard culture, were analysed with our method, and the gene encoding VT2 was detected in one cheese sample. The results suggest that the described PCR method can serve as a valuable tool for the surveillance of VTEC contamination of foods.
产生志贺毒素（VTs）的致病性大肠杆菌菌株已被确认为人类疾病的一个病因，因此迫切需要快速灵敏的检测方法以确保食品安全，尤其是碎牛肉的安全。我们应用了两种巢式聚合酶链反应（PCR）检测方法来检测编码VT1和VT2的基因，而不考虑细菌的血清型。结合直接样品制备方案，我们能够在10克碎牛肉中检测出约110个菌落形成单位（CFU）的产志贺毒素大肠杆菌（VTEC）。当加入6小时增菌步骤后，我们发现检测限为每10克碎牛肉中有1至10个细菌细胞。为评估我们的检测系统，我们检测了30份来自瑞士伯尔尼肉店的碎牛肉样品。其中一个样品的VT1和VT2基因PCR检测结果均为阳性，表明存在产志贺毒素大肠杆菌。最后，我们用我们的方法分析了20份经标准培养显示含有大肠杆菌菌株的食品匀浆，在一个奶酪样品中检测到了编码VT2的基因。结果表明，所描述的PCR方法可作为监测食品中VTEC污染的有价值工具。
