十种食源性致病菌的多重PCR快速检测方法

为建立能够同时检测食品中单核细胞增生李斯特氏菌、沙门氏菌属、克罗诺杆菌属、志贺氏菌属、金黄色葡萄球菌、副溶血性弧菌、大肠埃希氏菌O157:H7、铜绿假单胞菌、粪链球菌、产气荚膜梭菌等10种食源性致病菌的多重PCR方法,通过特异性引物的设计、引物特异性验证、引物灵敏度验证和多重PCR检测体系主要反应条件优化,建立多重PCR检测体系,并对其特异性、灵敏度以及人工感染样品应用进行评价。结果表明,建立的多重PCR检测体系可以扩增出10种食源性致病菌的特异目标条带,无非特异扩增。测序结果与目的基因序列进行比对,其序列同源性高达98%,体系灵敏度可达10^-1 ng/μL。人工污染样品应用结果表明,采用多重PCR方法简单快速,仅需简单增菌,检出限可达10 CFU/mL,整个检测时间在48 h以内。建立的多重PCR检测体系特异性强、灵敏度较高,与检验机构实际检测工作联系紧密,具有推广应用价值。     

应用可视芯片技术检测食品中常见致病菌的方法研究

利用特异性引物进行PCR扩增,并利用固定于可视芯片的特异探针与扩增产物进行杂交反应加以鉴定。利用可视芯片技术可以准确的检出沙门氏菌属和金黄色葡萄球、小肠结核肠炎耶尔森氏菌、单核细胞增生李斯特氏菌3种食品中常见致病菌,检测灵敏度可达8.5×101cfu/mL。利用可视芯片准确灵敏使用便捷的优点,建立了食品中常见致病菌鉴定方法,为食源性致病菌检测提供了一项快速有效的方法。     

GeXP多重聚合酶链式反应法检测5种常见食源性致病菌

目的建立一种基于GeXP(GenomeLab~(TM) eXpress Profiling)遗传分析系统的5种常见食源性致病菌检测的新技术。方法针对5种常见食源性致病菌(沙门菌、大肠埃希菌O157∶H7、单核细胞增生李斯特菌、志贺菌和副溶血性弧菌)分别进行基因序列比对(invA、rfbE、PfrA、IpaH、tlh基因),设计特异性引物,建立并优化GeXP多重聚合酶链式反应(PCR)体系,评价其特异性和灵敏性,并初步应用于未知菌株和人工污染样品的检测。结果 GeXP多重PCR法可实现在5 h内同时对5种常见食源性致病菌进行检测,且检测灵敏度可低至10~3 CFU/mL。多重体系中各引物对各目标菌有较强特异性,未检出其他非目标菌。结论本方法可有效提高检测效率,为食源性致病菌的快速高通量检测提供了参考思路。     

靶序列富集多重PCR结合DHPLC同时检测5种食源性致病菌

目的建立同时检测沙门氏菌、单核细胞增生李斯特氏菌、大肠埃希氏菌O157、金黄色葡萄球菌和志贺氏菌5种食源性致病菌的简便、灵敏的高通量方法。方法根据GenBank公布的5种致病菌的特异性靶基因序列,设计5对特异性引物,与通用引物连接构成复合引物。经过反应条件的优化,建立了5种致病菌的靶序列富集多重PCR(target enriched multiplex PCR,Tem-PCR)扩增方法,扩增产物采用变性高效液相色谱(denaturing high-performance liquid chromatography,DHPLC)技术进行检测。结果采用Tem-PCR-DHPLC方法,检测48株试验菌株,未发现非特异性结果。对5种致病菌检测灵敏度,除金黄色葡萄球菌为620 cfu/mL外,其余都小于100 cfu/mL。对4种样品的检测结果与国家标准方法相符合。结论 Tem-PCR-DHPLC检测方法,相比传统多重PCR方法,能有效地解决引物扩增效率不均衡的问题,不需优化引物浓度,方法特异性强,灵敏度高,具有较好的实用性。     

应用基因芯片技术检测肉及肉制品中5种致病菌

建立一种运用多重聚合酶链式反应(PCR)结合基因芯片技术检测大肠埃希氏菌、沙门氏菌、金黄色葡萄球菌、志贺氏菌和单核细胞增生李斯特菌5种食源性致病菌的快速、准确、灵敏的方法。分别选取编码大肠埃希氏菌的slt基因、沙门氏菌invA基因、金黄色葡萄球菌nuc基因、志贺氏菌ipaH基因和单核细胞增生李斯特菌inlA基因,并以细菌16S rDNA基因作为阳性对照,设计引物和探针,进行多重PCR扩增,产物与含特异性探针的芯片杂交。结果表明：该基因芯片可同时特异性地检测5种致病菌,多重PCR检测灵敏度为20pg,而DNA芯片检测灵敏度可达2pg;用所制备的基因芯片检测实际肉及肉制品样品,准确率高于传统培养法。所建立的基因芯片检测方法特异性好、灵敏度高,可为食源性致病菌的检测提供理想手段。     

3种食源性致病菌多重PCR检测体系的建立

目的:探究用PCR方法检测食品中金黄色葡萄球菌(Staphylococcus aureus)、沙门氏菌(Salmonella spp.)及志贺氏菌(Shigella spp.)的检测灵敏度,建立快速检测3种食源性致病菌的多重PCR方法。方法:分别依据金黄色葡萄球菌的fem A、沙门氏菌的hil A基因及志贺氏菌的ipa H基因设计3对特异性引物,对3对引物进行多重PCR反应体系构建与优化。结果:建立的多重PCR方法具有灵敏度高、特异性强、方便快捷的优点。结论:研究结果为上述3种食源性致病菌快速检测试剂盒的研发及在食品安全检测工作中的应用提供了重要技术保障。     

食源性致病菌多重实时荧光PCR检测扩增内标的构建及评价

多重实时荧光PCR在食源性致病菌检测中具有重要的作用,扩增内标(IAC)可用来指示其检测过程中可能出现的假阴性检测结果。采用来源于人类腺病毒基因的一段序列设计IAC,并对其检测特异性、扩增效率以及与目的致病菌基因组DNA的抗干扰扩增能力进行了评估。结果表明,本IAC引物在供试菌株中均没有非特异性扩增结果,扩增效率达99.44%,而且对供试沙门氏菌(Salmonella spp.)、大肠杆菌O157:H7(Escherichiacoli O157:H7)以及单核细胞增生李斯特菌(Listeria monocytogenes)的多重实时荧光PCR扩增没有任何干扰,在食源性致病菌多重检测技术的建立中具有广泛的应用前景。     

多重实时荧光定量PCR同时检测冷冻蔬菜中4种食源性致病菌

目的 建立一种基于TaqMan探针的多重实时荧光定量PCR(multiplex quantitative real-time PCR, multiplex qPCR)同时检测冷冻蔬菜中4种食源性致病菌的方法。方法 针对金黄色葡萄球菌nuc基因、痢疾志贺菌rfc基因、沙门氏菌invA基因、单增李斯特氏菌hly基因, 设计4对引物和探针, 优化反应体系, 建立稳定的多重qPCR反应体系。通过阳性菌株污染的方法验证体系的特异性, 并确定了冷冻蔬菜样品在细菌水平的检出限。结果 各对引物和探针对目标菌有较强的特异性, 对其他非目标菌进行检测均未检出, 人工污染冷冻蔬菜中志贺菌的检出限为102 CFU/g, 沙门氏菌和单增李斯特氏菌的检出限均为103 CFU/g, 金黄色葡萄球菌的检出限为104 CFU/g。结论 本研究可以实现冷冻蔬菜样品中4种致病菌qPCR高效检测。     

多重PCR检测婴幼儿配方奶粉中3种食源性致病菌

为建立一种能够同时检测婴幼儿配方奶粉(Powdered Infant Formula,PIF)中克罗诺杆菌、沙门氏菌和金黄色葡萄球菌3种食源性致病菌的多重PCR检测方法。通过单重PCR验证了9对引物的特异性,筛选出其中3对特异性好的引物建立了多重PCR体系,对其特异性和灵敏度进行评价,并将其应用于人工污染PIF中3种食源性致病菌的检测。结果表明,针对克罗诺杆菌、沙门氏菌和金黄色葡萄球菌等3种食源性致病菌所筛选的3对引物分别能扩增出469、638和796 bp的目的条带,具有高度特异性。多重PCR检测体系的最佳退火温度为55℃,最佳Mg²⁺浓度为2.00 mmol/L,最佳引物浓度为400 nmol/L。在此条件下3种目的菌在10² CFU/mL均可同时扩增出较清晰条带。将建立的多重PCR检测体系应用于人工污染PIF中3种食源性致病菌的检测,其检出限达到10³ CFU/g。本研究初步建立了一种能准确、快速、特异性的检测PIF中克罗诺杆菌、沙门氏菌和金黄色葡萄球菌的多重PCR方法,适用于PIF中3种常见的食源性致病菌的快速检测。     

3 种食源性致病菌Tem-PCR检测方法的建立

应用靶序列富集多重聚合酶链式反应（target-enriched multiplex-polymerase chain reaction,Tem-PCR）技术建立金黄色葡萄球菌、沙门氏菌和志贺氏菌3 种食源性致病菌的快速检测方法。分别以金黄色葡萄球菌femA基因、沙门氏菌invA基因和志贺氏菌ipaH基因为靶基因,设计3 对特异性引物,并与通用引物连接组成Tem-PCR引物,通过反应条件优化,建立了Tem-PCR检测方法。结果显示,建立的Tem-PCR方法特异性强,对沙门氏菌、金黄色葡萄球菌和志贺氏菌的检测灵敏度分别为1.1×103、2×103 CFU/mL和1.2×103 CFU/mL。Tem-PCR检测方法有效地解决了传统多重PCR引物扩增效率不均衡的问题。     

SIMULTANEOUS DETECTION OF LISTERIA MONOCYTOGENES, STAPHYLOCOCCUS AUREUS, SALMONELLA ENTERICA AND ESCHERICHIA COLI O157:H7 IN FOOD SAMPLES USING MULTIPLEX PCR METHOD

In this study, one multiplex polymerase chain reaction (MPCR) assay was developed for simultaneous detection of four foodborne pathogens, i.e., Listeria monocytogenes, Staphylococcus aureus, Salmonella enterica and Escherichia coli O157:H7. Five specific primer pairs were designed based on the nucleotide sequences of hemolysin gene (hly) of Listeria monocytogenes, thermostable nuclease gene (nuc) of Staphylococcus aureus, invasion gene (invA) of Salmonella enterica, shiga-like toxin gene (stx) and intimin gene (eae) of Escherichia coli O157:H7 in this assay. The specificity and sensitivity of the MPCR method were validated, and the limit of detection (LOD) of this method was about 10 copies. One cfu/mL each of these foodborne pathogens spiked in practical food samples, i.e., ground meat, beef, pork, fish, shrimp, cheese, canola leaf and cabbage, could be detected simultaneously after 24 h enrichment at a rate of 87.5%, indicating that the established MPCR detection method was effective and suitable for practical use.

PRACTICAL APPLICATIONS

This study presents a quick and effective identification method to simultaneous monitor four foodborne pathogens in food samples. The specificity and sensitivity of this method can be used to unambiguously identify these four foodborne pathogens in practical food samples based on the species-specific genes. Therefore, this detection method is applicable for surveillance measures of these four foodborne pathogens in the food production chain.     

高分辨率溶解曲线检测9种食源性致病菌方法的建立

当今食源性疾病已成为一个全球关注的食品卫生问题,常见的细菌性食物中毒的病原菌有:致病性大肠杆菌(特别是出血性大肠杆菌O157:H7)、沙门氏菌、志贺氏菌、致病性弧菌(包括霍乱弧菌和副溶血弧菌)、金黄色葡萄球菌、单增李斯特菌、空肠弯曲菌以及阪崎克罗诺杆菌等。单独检测一种致病菌已无法满足现今社会对同时高效检测多种致病菌的要求,为建立一种同时对上述9种食品中常见致病菌的检测方法,本研究分别以上述9种菌的特异性基因为靶基因,创新性地结合一对通用引物,建立能同时检测多种食源性致病菌的多重HRM-real time PCR检测体系。结果表明该多重HRM-real time PCR检测体系通过两管PCR反应可对上述9种食品中常见致病菌进行有效的检测与区分,且具有良好的特异性和灵敏度。     

Optimization of rapid detection of Escherichia coli O157:H7 and Listeria monocytogenes by PCR and application to field test

For rapid detection of Escherichia coli O157:H7 and Listeria monocytogenes, simple methods for sample preparation and PCR were established and applied to a field test. To improve specificity, primer sets LP43-LP44 and C(+)-D(-) were selected for E. coli O157:H7 and L. monocytogenes, respectively. Through centrifugation and partial heat treatment after enrichment, E. coli O157:H7 and L. monocytogenes were detected at 1 initial CFU without genomic DNA extraction in the culture and with artificially inoculated food samples including milk, chicken, ham, and pork. Based on the optimized PCR method, a feasibility test was carried out using randomly collected field samples. To remove false positives and false negatives, a PCR method using several primer sets, including the optimized primer set, and a standard culture method were used. With the PCR detection and standard culture methods, two pork samples were positive for L. monocytogenes after enrichment, indications that the PCR assay could be effectively used for rapid, sensitive, and species-specific detection of foodborne pathogens.     

Establishment and preliminary application of oligonucleotide microarray assay for detection of food-borne toxigenic microorganisms

Rapid, high-throughput and accurate detection and identification of food-borne toxigenic microorganisms is crucial for food safety nowadays. An oligonucleotide microarray was designed and established and was applied to detect common food-borne toxigenic microorganisms in this study. PCR amplification of marker genes and 16S rRNA gene of 14 toxigenic bacteria and fungi using specific primers and oligo probes residing in these genes were employed and designed to fabricate the microarray. Optimization of hybridization conditions was implemented. The optimal conditions for hybridization were 51 °C for 30 min. Furthermore, the ratio of biotin labeled to unlabeled primer for PCR amplification was also optimized to enhance specific hybridization of the microarray. Specificity, sensitivity (710 CFU/mL), and reproductivity assessment confirmed the practicability of the microarray. Finally, this microarray was successfully applied to detect 6 common toxigenic microorganisms from 328 food samples. The established microarray may provide potential for rapid detection and identification of toxigenic microorganisms from foods.     

沙门氏菌重组酶聚合酶检测方法的建立及应用

摘 要：建立一种重组酶聚合酶扩增技术（recombinase polymerase amplification,RPA）检测沙门氏菌（Salmonella）的方法。本研究依据沙门氏菌侵袭蛋白A基因（invA）的保守序列设计特异性引物,通过对反应时间的优化,建立的RPA方法在38?℃水浴锅中恒温反应20?min,即可实现对目的片段的有效扩增;除沙门氏菌外,其他26?种食源性致病菌均无扩增,具有良好的特异性;以沙门氏菌基因组DNA作为模板,该方法的检测灵敏度为1.1×10－3?ng/μL,与本研究应用的实时荧光聚合酶链式反应（real-time polymerase chain reaction,PCR）方法一致;人工污染实验表明,当羊肉、鸡肉和西兰花样品污染量为4?CFU/25?g,增菌8?h,即可通过RPA方法检出沙门氏菌。在人工污染实验中,RPA和PCR检测结果一致。本研究建立的沙门氏菌的RPA检测方法特异性强、操作简单、为食源性致病菌的鉴定提供了一种新的方向。     

A novel multiplex PCR assay for rapid and simultaneous detection of five pathogenic bacteria: Escherichia coli O157:H7, Salmonella, Staphylococcus aureus, Listeria monocytogenes, and Vibrio parahaemolyticus

Rapid and sensitive detection techniques for foodborne pathogens are important to the food industry. However, traditional detection methods rely on bacterial culture in combination with biochemical tests, a process that typically takes 4 to 7 days to complete. Thus, this study was conducted to address the issue of time lag inherent in traditional methods by developing a novel PCR assay for each of five foodborne pathogenic bacteria. This new system consists of a simultaneous screening method using multiplex PCR in a single reaction tube for the rapid and sensitive detection of each of the five bacteria. Specific primers for multiplex PCR amplification of the Shiga-like toxin (verotoxin type II), femA (cytoplasmic protein), toxR (transmembrane DNA binding protein), iap (invasive associative protein), and invA (invasion protein A) genes were designed to allow simultaneous detection of Escherichia coli O157:H7, Staphylococcus aureus, Vibrio parahaemolyticus, Listeria monocytogenes, and Salmonella, respectively. To confirm the specificity of each primer pair for the respective target gene, three types of experiments were carried out using boiled cell lysates and their DNAs. In the multiplex PCR with mixed DNA samples, specific bands for corresponding genes were simultaneously detected from a single reaction. The detection of all five foodborne pathogenic bacteria could be completed in less than 24 h with this novel PCR method.     

Polyester Cloth-Based Hybridization Array System for Identification of Enterohemorrhagic Escherichia coli Serogroups O26, O45, O103, O111, O121, O145, and O157

A cloth-based hybridization array system (CHAS) was developed for the identification of foodborne colony isolates of seven priority enterohemorrhagic Escherichia coli (EHEC-7) serogroups targeted by U. S. food inspection programs. Gene sequences associated with intimin; Shiga-like toxins 1 and 2; and the antigenic markers O26, O45, O103, O111, O121, O145, and O157 were amplified in a multiplex PCR incorporating a digoxigenin label, and detected by hybridization of the PCR products with an array of specific oligonucleotide probes immobilized on a polyester cloth support, with subsequent immunoenzymatic assay of the captured amplicons. The EHEC-7 CHAS exhibited 100 % inclusivity and 100 % exclusivity characteristics with respect to detection of the various markers among 89 different E. coli strains, with various marker gene profiles and 15 different strains of non-E. coli bacteria.     

聚合酶链式反应-变性高效液相色谱法检测5种食源性致病菌

目的建立聚合酶链式反应与变性高效液相色谱(polymerase chain reaction-denaturing high-performanceliquid chromatography,PCR-DHPLC)相结合的方法,快速检测5种食源性致病菌(沙门菌、副溶血性弧菌、福氏志贺菌、大肠埃希菌O157∶H7和单核细胞增生李斯特菌)。方法针对16S rRNA基因保守区设计引物,PCR扩增产物用变性高效液相色谱仪检测,并进行敏感性、特异性、检出率等指标测定。结果柱温61.4℃时,5种致病菌PCR产物分别呈现特异DHPLC色谱图,保留时间均为7min左右。对沙门菌、副溶血性弧菌和单核细胞增生李斯特菌检出限均为5～10CFU/ml,福氏志贺菌和大肠埃希菌O157∶H7均为1～5CFU/ml。对83株目的分离株的检出符合率为100%,38株非目的分离株检测均为阴性;对人工污染食品中的5种致病菌均可正确检出。结论该PCR-DHPLC方法具有较高的敏感性和特异性,可用于食品中5种食源性致病菌的高通量快速检测。     

应用基因芯片技术检测食源性腹泻致病大肠杆菌

目的基因芯片技术在食源性致病大肠杆菌检测中的建立与应用。方法对菌株进行预处理,通过溴化十六烷基三甲铵(cetyltrime thylammonium ammonium bromide,CTAB)方法提取细菌中的基因组DNA并去除其中的杂质,利用提取的基因组设计引物序列和探针序列,设计完成后对致病大肠杆菌致病大肠杆就基因芯片进行杂交与洗涤,使用扫描仪对处理过的基因芯片进行扫描实现食源性致病大肠杆菌的检测。结果在病原菌按不同程度稀释的情况下,与传统的病原分离鉴定检测方法相比,将基因芯片技术应用在食源性致病大肠杆菌致检测中,能够明显的检测出荧光标记的病原菌。结论该方法的灵敏度更高,可以解决传统的致病大肠杆菌检测方法灵敏度较低,病原处于较低的感染状态时难以检出的问题。     

Optimization and Application of a Custom Microarray for the Detection and Genotyping of E. coli O157:H7 in Fresh Meat Samples

DNA microarrays are promising high-throughput tools for multiple pathogen detection. Currently, the performance and cost of this platform has limited its broad application in identifying microbial contaminants in foods. In this study, an optimized custom DNA microarray with flexibility in design and content for foodborne pathogen detection was developed through the systematic evaluation of spotting buffers, probe lengths, scanning conditions, and nucleic acid amplification and labeling strategies. Briefly, by robotic contact printing, a spotting solution of 50 % dimethylsulfoxide produced uniform and high-quality spots on UltraGAPS glass slides coated with aminopropyl silane. The use of 60 % photomultiplier tube gain in scanning ～70-mer oligonucleotide probes resulted in strong signals and low background. For sample preparation, multiplex PCR amplification coupled with fluorescent labeling of DNA using the Klenow fragment and random hexamers achieved higher specificity than whole genome random amplification. To minimize the cost of the assay, the quantities of probes, Klenow fragment, and Cy5 were substantially reduced in each assay without noticeably affecting the detection efficiency. Applying the optimized microarray assay to 26 fresh meat samples, three different isolates of Escherichia coli O157:H7 were found in four individual packages, demonstrating that the assay has a great potential for identifying and genotyping multiple pathogens in a real food system.