多重荧光PCR-熔解曲线法同时检测常见病原真菌方法学的建立及诊断价值

目的建立多重荧光PCR-熔解曲线法，并评价其同时检测假丝酵母菌、曲霉菌及新型隐球菌的诊断价值。 方法建立多重荧光PCR-熔解曲线法并对其检测体系进行优化。收集临床高度怀疑为侵袭性真菌感染（IFI）的各类临床样本179例，其中血液65例、深部痰液35例、尿液30例、脑脊液18例、胸腹水12例、肺泡灌洗液10例、新鲜肺组织9例。通过敏感性、特异性、重复性实验验证多重荧光PCR-熔解曲线法的检测性能，并应用受试者工作特征（ROC）曲线评价该方法的诊断效能。 结果建立的多重荧光PCR-熔解曲线法可同时检测8种常见病原真菌，包括4种假丝酵母菌（白假丝酵母菌、热带假丝酵母菌、光滑假丝酵母菌、克柔假丝酵母菌）、3种曲霉菌（烟曲霉、黄曲霉、黑曲霉）和新型隐球菌。其最低检测限为1 × 10⁴ cfu/mL，且常见细菌无扩增反应，重复性实验解链温度波动小于0.5 ℃。179例临床样本中，以培养法、镜检法、病理诊断等"金标准"方法诊断IFI阳性为112例，多重荧光PCR-熔解曲线法检测阳性为96例。多重荧光PCR-熔解曲线法同时检测假丝酵母菌、曲霉菌及新型隐球菌的敏感度为0.857，特异度为0.970，阳性预测值为0.980，阴性预测值为0.802，ROC曲线下面积为0.914，95%置信区间为0.868 ~ 0.959，P < 0.001。 结论本研究建立的多重荧光PCR-熔解曲线法可快速、准确、高通量同时检测假丝酵母菌、曲霉菌及新型隐球菌，对于IFI的早期诊断具有重要意义。     

Oral gram-positive bacterial DNA-based identification of saliva from highly degraded samples

Analyzing degraded evidence is an important challenge in forensic casework. Saliva remaining at a crime scene may deteriorate, due to various factors, making it difficult to identify. This study aims to clarify the efficacy of oral gram-positive and -negative bacterial DNA-based identification of saliva for analyzing highly degraded samples. Saliva samples were subjected to three different degradation treatments (heat denaturation: 40–80 °C in wet conditions; microbial decomposition: 1–5 days in humid soil; and ultraviolet (UV) irradiation: 0.01–1 J/cm²). We compared saliva markers’ detectability from the degraded samples—oral gram-positive bacterial DNA (Streptococcus salivarius and Streptococcus oralis), oral gram-negative bacterial DNA (Veillonella atypica and Prevotella maculosa) and salivary α-amylase. Oral bacterial DNA was detected using a melting curve analysis following real-time PCR. The efficacy of short tandem repeats (STR) and mitochondrial DNA (mtDNA) analyses were also compared. All oral bacterial DNA were detected with specific melting peaks from the heat-denatured samples, while neither catalytic nor immunochromatographic tests detected salivary α-amylase from the heat (80 °C) samples. The gram-positive bacterial DNA (S. salivarius and S. oralis) was detected from the microbial degradation (1–5 days) samples. In contrast, the gram-negative bacterial DNA (V. atypica and P. maculosa) and salivary α-amylase were not detected from samples treated for more than two days. UV exposure made bacterial DNA-based saliva identification difficult in a dose–dependent manner; however, UV irradiation did not influence protein-based saliva tests using salivary α-amylase as an indicator. As a result of STR and mtDNA typing, partial or null STR profiles were generated from the severely degraded (microbial (2–5 days) and UV (0.1–1 J/cm²) degradation) samples, but full mtDNA profiles were obtained from all degraded samples. The forensic applicability of bacterial DNA test evaluated, using mock case samples, indicates that the oral gram-positive bacterial DNA was more resistant to degradation than the other markers. We conclude that the oral gram-positive bacterial DNA-based examination could be useful for identifying saliva from severely environmentally-exposed forensic samples as well as mtDNA typing.     

A highly sensitive 1-tube nested real-time RT-PCR assay using LNA-modified primers for detection of respiratory syncytial virus

Respiratory syncytial virus (RSV) causes serious respiratory tract infection worldwide. The relatively low RSV load makes it difficult to detect in frail, elderly, and severely immune-compromised patients. In the present study, we developed a locked nucleic acid–-based 1-tube nested real-time RT-PCR (OTNRT-PCR) assay with the advantages of extremely high sensitivity, facile operability, and less likelihood of cross-contamination. The sensitivity, specificity, and clinical performance of the OTNRT-PCR assay were compared in parallel with a conventional TaqMan probe-based real-time PCR (qRT-PCR) assay and a traditional 2-step nested RT-PCR assay. The limit of detection of the OTNRT-PCR assay was 1.02?×?10^?1 TCID50/mL, equivalent to the traditional 2-step nested RT-PCR assay and 25-fold lower than the qRT-PCR assay. Of 616 nasopharyngeal aspirates tested, 143 RSV-negative samples by qRT-PCR were confirmed as positive by sequencing the OTNRT-PCR products. We therefore conclude that OTNRT-PCR is more sensitive than qRT-PCR for detection of RSV in clinical samples.     

荧光杂交探针实时聚合酶链式反应快速检测甘露聚糖结合凝集素启动子区基因变异方法的建立

目的建立用荧光杂交探针实时聚合酶链式反应（Real-timePCR）检测人甘露聚糖结合凝集素（MBL）启动子区基因变异新型的基因分型法——Tm基因分型法。方法收集30例健康献血员外周抗凝全血,提取基因组DNA。通过LightCycler实时PCR仪描绘扩增的目标DNA片段的熔解曲线,根据熔解温度（Tm）峰值判定待测标本的基因变异类型。最后,用基因测序法检测PCR产物来验证Tm基因分型法的准确性。结果建立了新型的Tm基因分型法,且测定PCR产物的时间仅180min,检测结果与测序法完全吻合。结论Tm基因分型法检测人MBL启动子区基因变异快速、准确,重复性好,具有广泛的临床应用前景。     

熔解曲线分析法用于HPA-15基因分型的研究

目的探讨熔解曲线分析法用于HPA-15基因分型,了解大连地区汉族人群HPA-15基因多态性。方法设计合成HPA-15等位基因特异性引物和1条公共引物,其中在2条等位基因特异性引物的5'末端分别加入具有不同长度并富含GC碱基的序列。使用这3条引物,进行实时PCR反应。在PCR反应后,进行熔解曲线分析,依据PCR产物熔解温度的差异,进行基因分型。应用熔解曲线分析法和常规PCR-SSP法对100名大连地区汉族人群的血液标本进行HPA-15基因分型。此外对熔解曲线分析法的重复性进行评价。结果 100个血液标本的熔解曲线分析法和常规PCR-SSP法的基因分型结果是完全一致的。10个血标本的2次熔解曲线分析结果是一致的。大连地区汉族人群HPA-15a、-15b基因频率分别为0.58和0.42。大连地区汉族人群与国内部分地区汉族人群相比,HPA-15等位基因频率的差异无统计学意义(P>0.05)。与新疆维吾尔族人群相比,HPA-15等位基因频率差异有统计学意义(P<0.05)。结论 HPA的熔解曲线基因分型方法具有快速、简单、准确、通量高、重复性好等优点,要优于常规的PCR-SSP法。在国内HPA-15等位基因分布存在着种族差异。     

药品卫生学检查中培养基加温熔化次数对菌检率影响的研究

目的确保药品质量检测的准确性。方法将藤黄微球菌、白色念珠菌按2005年版《中国药典》要求配制成一定浓度的供试菌液。另各取已处理好的玫瑰红钠琼脂培养基、氯化三苯四氮唑培养基25ml,分别对应倾注于上述2种供试菌液中,制成平板,置于35℃培养48h和25℃培养72h,记录菌落数(从培养基冷却到加温溶解6次),并将结果进行比较。结果将微生物限度检查用培养基加温熔化3次以上,随着加温次数增加,菌检出量将明显降低。结论配制培养基时,需盛装在大小不同的容器中,并根据送检样品的多少,选用不同的培养基;根据疾病谱变化规律,将淡、旺季药品酌情配制,尽可能集中配制,及时送检。     

Severity of foraminal lumbar stenosis and the relation to clinical symptoms and response to periradicular infiltration—introduction of the “melting sign”

Background Context

Nerve root compression causing symptomatic radiculopathy can occur within the intervertebral foramen. Sagittal magnetic resonance imaging (MRI) sequences are reliable in detection of nerve root contact to intraforaminal disc material, but a clinically relevant classification of degree of contact is lacking.

熔解曲线分析检测临床常见4种革兰阳性菌的方法建立

目的 构建熔解曲线分析法同时检测4种临床常见革兰阳性病原菌,为临床感染性疾病的诊疗提供快速、敏感的分子生物学检测信息.方法 选取临床最常见的革兰阳性病原菌:金黄色葡萄球菌、表皮葡萄球菌、屎肠球菌、粪肠球菌做为本课题研究的检测菌种.根据检测菌种的不同,分别选取不同菌种的特异性靶序列,设计种特异性引物.对种特异性引物分别用标准菌株、临床分离目标菌株、临床分离非目标菌株、非细菌性病原体以及人源基因组DNA进行常规PCR扩增以及扩增产物测序,验证引物的特异性.对目标菌种引物进行荧光PCR预实验,筛选Tm值差异较大的多对引物,进行熔解曲线分析法实验,并对熔解曲线法的反应条件与反应体系进行优化.对优化后的熔解曲线法进行特异性验证.通过检测加入人血液中的不同细菌浓度对该方法进行敏感性分析.应用所构建的方法分别检测临床分离目标菌种各20株,分析每种菌种的熔解曲线图,熔点温度(Tm值)及其标准差(SD)的变化,评价所构建方法的稳定性.结果 ①对所设计的种特异性引物经常规PCR扩增产物电泳分析显示,目标菌株均有目的特异性扩增产物,非目标菌株、非细菌性病原体以及人源基因组DNA未出现特异性电泳条带.特异性扩增产物测序所得序列比对分析显示与目的菌种序列相符.②对金黄色葡萄球菌、表皮葡萄球菌、屎肠球菌、粪肠球菌的4对引物同时进行熔解曲线分析和mecA基因熔解曲线分析的条件优化结果:预变性温度94℃、120s,变性温度94℃、20s:退火温度53℃、12s;延伸温度68℃、13s;扩增循环数为40个循环,熔解曲线分析温度75℃～95℃.最佳的引物浓度为300nmol/L.③所建立的方法经特异性分析显示,上述4种目标菌种均有特异性熔解曲线,Tm值依次为81.02℃;80.32℃;82.37℃:83.10℃,峰高(cm)/峰宽(cm)均大于2.6,以此为典型的熔解曲线判断标准,则非目标菌、非细菌性病原体以及人源基因组DNA分析未见典型的熔解曲线.④方法的敏感性分析显示,上述4种目标菌和mecA基因可检测到的血液细菌浓度依次为:550、520、470、500与203CFU/mL.⑤对上述4菌和MRSA的临床分离菌各20株进行检测,结果显示,其平均Tm值依次为(80.96±0.688)℃,(80.20±0.729)℃,(82.42±0.599)℃,(83.20±0.713)℃和(80.11±0.15)℃.结论 本研究所设计的针对金黄色葡萄球菌、表皮葡萄球菌、屎肠球菌、粪肠球菌和mecA基因检测引物具有较好的菌种特异性,可用于相应病原菌熔解曲线分析法的建立;所构建的熔解曲线法具有较好的特异性、敏感性和稳定性;并具有快速、简便、成本低廉的特点,可用于临床样本的检测;但葡萄球菌属内和肠球菌属内的Tm值较接近,必要时,可进一步用单对引物检测分析以鉴定到种.     

Multiplex high resolution melting assay for estimation of Porcine Endogenous Retrovirus (PERV) relative gene dosage in pigs and detection of PERV infection in xenograft recipients

Porcine Endogenous Retrovirus (PERV) poses an infectious risk in the field of xenotransplantation. This risk may be mitigated by breeding selectively animals bearing favorable PERV genetic characteristics including pigs with low levels of PERV integrated in the genome. A real-time quantitative polymerase chain reaction (PCR) assay employing the Roche High Resolution Melting (HRM) Master was used to estimate the relative gene dosage of PERV pol integrated within the pig genome. When assessed across 99 pigs of the Auckland Island breed numerous animals bearing low gene dosage were identified. The assay was adapted further to perform multiplex PCR for the detection of PERV infection within xenograft recipients. Besides PERV, amplification targets for the multiplex PCR include a pig cell marker for the determination of microchimerism and an internal amplification control (IAC) to assess the efficiency of nucleic acid isolation and effects of PCR inhibition. When 12 patients who had received porcine islet transplants were tested no evidence of PERV infection was found. The assay was shown to be specific, highly reproducible with superior performance over conventional nested PCR. This assay can be used as both a screening tool for PERV proviral levels within donor pigs and as a diagnostic tool to examine PERV transmission in human patients treated with porcine xenotransplantation material.