Stefan A, Scaramagli S, Bergami R, Mazzini C, Barbanera M, Perelle S, Fach P
Laboratorio COOP ITALIA, Via del Lavoro 6/8, Casalecchio di Reno, Bologna, Italy.
Can J Microbiol. 2007 Mar;53(3):337-42. doi: 10.1139/W06-142.
This work aimed to compare real-time polymerase chain reaction (PCR) with the commercially available enzyme-linked fluorescent assay (ELFA) VIDAS ECOLI O157 for detecting Escherichia coli O157 in mincemeat. In addition, a PCR-based survey on Shiga-toxin-producing E. coli (STEC) in mincemeat collected in Italy is presented. Real-time PCR assays targeting the stx genes and a specific STEC O157 sequence (SILO157, a small inserted locus of STEC O157) were tested for their sensitivity on spiked mincemeat samples. After overnight enrichment, the presence of STEC cells could be clearly determined in the 25 g samples containing 10 bacterial cells, while the addition of five bacteria provided equivocal PCR results with Ct values very close to or above the threshold of 40. The PCR tests proved to be more sensitive than the ELFA-VIDAS ECOLI O157, whose detection level started from 50 bacterial cells/25 g of mincemeat. The occurrence of STEC in 106 mincemeat (bovine, veal) samples collected from September to November 2004 at five different points of sale in Italy (one point of sale in Arezzo, Tuscany, central Italy, two in Mantova, Lombardy, Northern Italy, and two in Bologna, Emilia-Romagna, upper-central Italy) was less than 1%. Contamination by the main STEC O-serogroups representing a major public health concern, including O26, O91, O111, O145, and O157, was not detected. This survey indicates that STEC present in these samples are probably not associated with pathogenesis in humans.
这项工作旨在比较实时聚合酶链反应（PCR）与市售的酶联荧光分析法（ELFA）VIDAS ECOLI O157用于检测碎肉中大肠杆菌O157的效果。此外，还介绍了一项基于PCR对意大利采集的碎肉中产志贺毒素大肠杆菌（STEC）的调查。针对stx基因和特定的STEC O157序列（SILO157，STEC O157的一个小插入位点）的实时PCR检测方法在加标的碎肉样品上进行了灵敏度测试。过夜富集后，在含有10个细菌细胞的25克样品中可以清楚地检测到STEC细胞的存在，而添加5个细菌时PCR结果不明确，Ct值非常接近或高于40的阈值。PCR检测被证明比ELFA-VIDAS ECOLI O157更灵敏，后者的检测水平从50个细菌细胞/25克碎肉开始。2004年9月至11月在意大利五个不同销售点（意大利中部托斯卡纳大区阿雷佐的一个销售点、意大利北部伦巴第大区曼托瓦的两个销售点以及意大利中北部艾米利亚-罗马涅大区博洛尼亚的两个销售点）采集的106份碎肉（牛肉、小牛肉）样品中STEC的检出率低于1%。未检测到代表主要公共卫生问题的主要STEC O血清群（包括O26、O91、O111、O145和O157）的污染。这项调查表明，这些样品中存在的STEC可能与人类发病机制无关。
