Foundation for Innovative New Diagnostics (FIND), Kampala, Uganda.
PLoS One. 2013 Sep 6;8(9):e72556. doi: 10.1371/journal.pone.0072556. eCollection 2013.
Light emitting diode (LED) fluorescence microscopy (FM) is an affordable, technology targeted for use in resource-limited settings and recommended for widespread roll-out by the World Health Organization (WHO). We sought to compare the operational performance of three LED FM methods compared to light microscopy in a cohort of HIV-positive tuberculosis (TB) suspects at an urban clinic in a high TB burden country.
Two spot specimens collected from TB suspects were included in the study. Smears were stained using auramine O method and read after blinding by three LED-based FM methods by trained laboratory technicians in the Infectious Diseases Institutelaboratory. Leftover portions of the refrigerated sputum specimens were transported to the FIND Tuberculosis Research Laboratory for Ziehl Neelsen (ZN) smear preparation and reading by experienced technologist as well as liquid and solid culture.
174 of 627 (27.8%) specimens collected yielded one or more positive mycobacterial cultures. 94.3% (164/174) were M. tuberculosis complex. LED FM was between 7.3-11.0% more sensitive compared to ZN microscopy. Of the 592 specimens examined by all microscopy methods, there was no significant difference in sensitivity between the three LED FM methods. The specificity of the LED FM methods was between 6.1% and 7.7% lower than ZN microscopy (P<0.001), although exclusion of the single poor reader resulted in over 98% specificity for all FM methods.
Laboratory technicians in routine settings can be trained to use FM which is more sensitive than ZN microscopy. Despite rigorous proficiency testing, there were operator-dependent accuracy issues which highlight the critical need for intensive quality assurance procedures during LED FM implementation. The low sensitivity of FM for HIV-positive individuals particularly those with low CD4 T cell counts, will limit the number of additional patients found by LED FM in countries with high rates of HIV co-infection.
发光二极管（LED）荧光显微镜（FM）是一种经济实惠的技术，针对资源有限的环境设计，世界卫生组织（WHO）推荐广泛推广。我们旨在比较三种 LED FM 方法与显微镜在高结核负担国家城市诊所的 HIV 阳性肺结核（TB）疑似患者中的操作性能。
本研究纳入了两名 TB 疑似患者采集的两个斑点标本。用金胺 O 法染色后，由经过培训的传染病研究所实验室技术人员对三种基于 LED 的 FM 方法进行盲法读取。冷藏的痰液标本的剩余部分被运送到 FIND 结核病研究实验室，由经验丰富的技术人员进行 Ziehl Neelsen（ZN）涂片准备和阅读，以及液体和固体培养。
627 份标本中 174 份（27.8%）采集的标本中一种或多种分枝杆菌培养呈阳性。94.3%（164/174）为结核分枝杆菌复合体。LED FM 比 ZN 显微镜敏感 7.3-11.0%。在所有显微镜方法检查的 592 份标本中，三种 LED FM 方法之间的敏感性无显著差异。与 ZN 显微镜相比，LED FM 方法的特异性低 6.1%-7.7%（P<0.001），尽管排除了单一的低读数者，所有 FM 方法的特异性均超过 98%。
在常规环境中，实验室技术人员可以接受培训使用 FM，FM 比 ZN 显微镜更敏感。尽管进行了严格的熟练程度测试，但存在操作人员依赖的准确性问题，这突出表明在 LED FM 实施期间需要进行密集的质量保证程序。FM 对 HIV 阳性个体，特别是 CD4 T 细胞计数较低的个体的敏感性较低，将限制 LED FM 在 HIV 合并感染率较高的国家发现的额外患者数量。
