Carney E, O'Brien S B, Sheridan J J, McDowell D A, Blair I S, Duffy G
The National Food Centre, Dunsinea, Castleknock, Teagasc, Ashtown, Dublin 15, Ireland.
Food Microbiol. 2006 Feb;23(1):52-9. doi: 10.1016/j.fm.2004.12.001.
This study investigated the prevalence and level of Escherichia coli O157 on samples of beef trimmings (n=1351), beef carcasses (n=132) and bovine head meat (n=132) in a beef slaughter plant in Ireland. The survey also included an assessment of the prevalence of virulence genes in the E. coli O157 isolates obtained. Samples were examined for the presence of E. coli O157 by direct plating on SMAC-CT and by enrichment/immunomagnetic separation (IMS) with plating of recovered immunobeads onto SMAC-CT agar. Presumptive E. coli O157 isolates were confirmed by PCR targeting a range of genes i.e. vt1, vt2, eaeA, hlyA, fliC(h7) and portions of the rfb (O-antigen encoding) region of E. coli O157. Enterobacteriaceae on head meat samples were estimated by direct plating onto Violet Red Bile Glucose agar. E. coli O157 was recovered from 2.4% (32/1351) of beef trimmings samples, at concentrations ranging from<0.70-1.61 log10 cfu g(-1). Of the 32 positive isolates, 31 contained the eaeA and hylA genes while 30/32 contained the fliC(h7) gene and 31/32 contained vt1 or vt2, or both vt genes. E. coli O157 was recovered from 3.0% (4/132) of carcass samples, at concentrations ranging from <0.70-1.41 log10 cfu g(-1). All of the carcass isolates contained the eaeA, hylA and fliC(h7) genes. E. coli O157 was recovered from 3.0% (3/100) of head meat samples, at concentrations of 0.7-1.0 log10 cfu g(-1). All of the head meat isolates contained the eaeA, hylA, fliC(h7) and vt2 genes. No head meat isolates contained the vt1 gene. Head meat samples (n=100) contained Enterobacteriaceae, at concentrations ranging from 0.70-3.0 log10 cfu g(-1). Overall, the qualitative and quantitative data obtained for E. coli O157 on beef trimming samples in this study could be employed as part of a quantitative risk assessment model.
本研究调查了爱尔兰一家牛肉屠宰厂中牛肉边角料样本（n = 1351）、牛胴体样本（n = 132）和牛头肉样本（n = 132）中大肠杆菌O157的流行率和含量水平。该调查还包括对所获得的大肠杆菌O157分离株中毒力基因流行率的评估。通过直接接种于SMAC - CT培养基以及通过富集/免疫磁珠分离（IMS）法（将回收的免疫磁珠接种到SMAC - CT琼脂上）来检测样本中是否存在大肠杆菌O157。通过针对一系列基因（即vt1、vt2、eaeA、hlyA、fliC(h7)以及大肠杆菌O157的rfb（编码O抗原）区域的部分片段）进行PCR，来确认推定的大肠杆菌O157分离株。通过直接接种于紫红胆盐葡萄糖琼脂来估算牛头肉样本中的肠杆菌科细菌。在2.4%（32/1351）的牛肉边角料样本中检测到大肠杆菌O157，含量范围为<0.70 - 1.61 log10 cfu g(-1)。在32株阳性分离株中，31株含有eaeA和hylA基因，30/32含有fliC(h7)基因，31/32含有vt1或vt2基因，或同时含有这两个vt基因。在3.0%（4/132）的胴体样本中检测到大肠杆菌O157，含量范围为<0.70 - 1.41 log10 cfu g(-1)。所有胴体分离株均含有eaeA、hylA和fliC(h7)基因。在3.0%（3/100）的牛头肉样本中检测到大肠杆菌O157，含量为0.7 - 1.0 log10 cfu g(-1)。所有牛头肉分离株均含有eaeA、hylA、fliC(h7)和vt2基因。没有牛头肉分离株含有vt1基因。100份牛头肉样本中含有肠杆菌科细菌，含量范围为0.70 - 3.0 log10 cfu g(-1)。总体而言，本研究中关于牛肉边角料样本中大肠杆菌O157获得的定性和定量数据可作为定量风险评估模型的一部分。
