摘要:目的 建立改良分子信标实时PCR快速检测大肠杆菌O 157 :H 7 的快速方法。 方法 根据GenBank公布O 157 :H 7 的rfbE保守序列，设计一对引物和改良分子信标探针，用FAM荧光剂标记探针的5'端，建立改良分子信标实时PCR检测O 157 :H 7 的反应体系，应用于食物中毒快速诊断和食品微生物检测。 结果 共检测11种细菌，只有大肠杆菌O 157 :H 7 有荧光信号，其余10种全无荧光信号，且与其他细菌无交叉反应，DNA灵敏度为64fg，菌液灵敏度为59cfu/ml或2cfu/PCR反应体系。应用改良分子信标实时PCR反应体系检测10株O 157 :H 7 均出现特异的荧光信号，无干扰。对89份食品样品进行检测，5份O 157 :H 7 实时PCR阳性，其余样品为阴性，检测仅需2h。5份阳性样本，经传统方法培养，有3份检出大肠杆菌O 157 :H 7 。 结论 改良分子信标实时PCR检测体系快速、灵敏度高，特异性强，可用于大肠杆菌O 157 :H 7 食物中毒的快速诊断和食品微生物检测，为食源性疾病的分子流行病学调查提供新的检测手段。

     关键词:大肠杆菌O 157 :H 7 ;改良分子信标;实时PCR

    Rapid Detection of E.coli O 157 :H 7 by using modified beacons and real-time PCR.

    HE Lian-hua，HUQing-hua，SHI Xiao-lu，et al.

    (Shenzhen Municipal Center for Disease Control and Prevention，Shenzhen518020，Guangdong，P.R.China)

    Abstract:Objective To establish a method for rapid detection of E.coli O 157 :H 7 from samples of contaminated food by using modified molecular beacons and real-time PCR. Methods The primers and modified molecular beacons were designed based on the core sequence of rfbE gene published on GenBank for detection of E.coli O 157 :H 7 .The probe was labeled with FAM at5'end.The molecular beacons and primer setwas tested against numerous strains from11different bacterial species and used for rapid detec-tion and diagnosis of ffod poisoning. Results For the modified molecular beacons-based real-time PCR assay ......