Liverpool School of Tropical Medicine, Liverpool, United Kingdom.
PLoS Med. 2011 Jul;8(7):e1001057. doi: 10.1371/journal.pmed.1001057. Epub 2011 Jul 12.
The diagnosis of tuberculosis (TB) in resource-limited settings relies on Ziehl-Neelsen (ZN) smear microscopy. LED fluorescence microscopy (LED-FM) has many potential advantages over ZN smear microscopy, but requires evaluation in the field. The aim of this study was to assess the sensitivity/specificity of LED-FM for the diagnosis of pulmonary TB and whether its performance varies with the timing of specimen collection.
Adults with cough ≥2 wk were enrolled consecutively in Ethiopia, Nepal, Nigeria, and Yemen. Sputum specimens were examined by ZN smear microscopy and LED-FM and compared with culture as the reference standard. Specimens were collected using a spot-morning-spot (SMS) or spot-spot-morning (SSM) scheme to explore whether the collection of the first two smears at the health care facility (i.e., "on the spot") the first day of consultation followed by a morning sample the next day (SSM) would identify similar numbers of smear-positive patients as smears collected via the SMS scheme (i.e., one on-the-spot-smear the first day, followed by a morning specimen collected at home and a second on-the-spot sample the second day). In total, 529 (21.6%) culture-positive and 1,826 (74.6%) culture-negative patients were enrolled, of which 1,156 (49%) submitted SSM specimens and 1,199 (51%) submitted SMS specimens. Single LED-FM smears had higher sensitivity but lower specificity than single ZN smears. Using two LED-FM or two ZN smears per patient was 72.8% (385/529, 95% CI 68.8%-76.5%) and 65.8% (348/529, 95% CI 61.6%-69.8%) sensitive (p<0.001) and 90.9% (1,660/1,826, 95% CI 89.5%-92.2%) and 98% (1,790/1,826, 95% CI 97.3%-98.6%) specific (p<0.001). Using three LED-FM or three ZN smears per patient was 77% (408/529, 95% CI 73.3%-80.6%) and 70.5% (373/529, 95% CI 66.4%-74.4%, p<0.001) sensitive and 88.1% (95% CI 86.5%-89.6%) and 96.5% (95% CI 96.8%-98.2%, p<0.001) specific. The sensitivity/specificity of ZN smear microscopy and LED-FM did not vary between SMS and SSM.
LED-FM had higher sensitivity but, in this study, lower specificity than ZN smear microscopy for diagnosis of pulmonary TB. Performance was independent of the scheme used for collecting specimens. The introduction of LED-FM needs to be accompanied by appropriate training, quality management, and monitoring of performance in the field.
Current Controlled Trials ISRCTN53339491. Please see later in the article for the Editors' Summary.
在资源有限的环境中，结核病（TB）的诊断依赖于齐-尼氏（ZN）染色显微镜检查。与 ZN 染色显微镜相比，LED 荧光显微镜（LED-FM）具有许多潜在的优势，但需要在现场进行评估。本研究的目的是评估 LED-FM 对肺结核的诊断的敏感性/特异性，以及其性能是否随标本采集时间的不同而变化。
连续纳入埃塞俄比亚、尼泊尔、尼日利亚和也门咳嗽≥2 周的成年人。使用 ZN 染色显微镜和 LED-FM 检查痰标本，并与培养作为参考标准进行比较。采用点-晨-点（SMS）或点-点-晨（SSM）方案采集标本，以探讨第一天就诊时在医疗机构采集前两次涂片（即在现场），然后第二天采集晨标本（SSM）是否能与通过 SMS 方案采集的涂片识别出相似数量的涂片阳性患者（即第一天采集一次现场涂片，然后在家采集晨标本，第二天采集第二次现场样本）。共纳入 529 例（21.6%）培养阳性和 1,826 例（74.6%）培养阴性患者，其中 1,156 例（49%）提交 SSM 标本，1,199 例（51%）提交 SMS 标本。单个 LED-FM 涂片的敏感性较高，但特异性较低。每位患者使用两个 LED-FM 或两个 ZN 涂片的敏感性分别为 72.8%（385/529，95%CI 68.8%-76.5%）和 65.8%（348/529，95%CI 61.6%-69.8%）（p<0.001），特异性分别为 90.9%（1,660/1,826，95%CI 89.5%-92.2%）和 98%（1,790/1,826，95%CI 97.3%-98.6%）（p<0.001）。每位患者使用三个 LED-FM 或三个 ZN 涂片的敏感性分别为 77%（408/529，95%CI 73.3%-80.6%）和 70.5%（373/529，95%CI 66.4%-74.4%）（p<0.001），特异性分别为 88.1%（95%CI 86.5%-89.6%）和 96.5%（95%CI 96.8%-98.2%）（p<0.001）。ZN 染色显微镜和 LED-FM 的敏感性/特异性在 SMS 和 SSM 之间没有差异。
LED-FM 对肺结核的诊断敏感性高于 ZN 染色显微镜，但特异性较低。性能不受标本采集方案的影响。引入 LED-FM 时需要伴随适当的培训、质量管理和现场性能监测。
当前对照试验 ISRCTN53339491。请稍后在文章中查看编辑摘要。
