Epicentre, Paris, France.
PLoS One. 2011;6(5):e20175. doi: 10.1371/journal.pone.0020175. Epub 2011 May 31.
Sputum microscopy is the only diagnostic for tuberculosis (TB) available at peripheral levels of health service in resource-poor countries. Its sensitivity is reduced in high HIV-prevalence settings. Sodium hypochlorite (NaOCl) specimen sedimentation prior microscopy and light-emitting diode (LED)-fluorescence microscopy (FM) can individually improve performance of microscopy. This study aimed to evaluate the performance of combined LED-FM and NaOCl sputum sedimentation for TB detection at peripheral level of health services.
A prospective study was conducted in an urban health clinic in Nairobi, Kenya. Three sputum specimens were collected over 2 days from consecutive TB suspects. Smears were prepared and stained with auramine O and Ziehl-Neelsen (ZN) methods. Bleach (3.5%) was added to the remaining specimen before overnight sedimentation at room temperature. Auramine O staining was performed on smears of sediment. A 4(th) specimen was collected for TB culture. Auramine smears were read under the same microscope as used for ZN smears, but equipped with the LED FluoLED™ fluorescence illuminator.
497 patients were included, and 1394 specimens collected. The yield of positive specimen was significantly increased after NaOCl sedimentation (24.9%) compared to direct LED-FM (20.6%) and direct ZN (20.3%). In detecting smear-positive patients, sensitivity was 78.5% for LED-FM after NaOCl sedimentation compared to 73.2% and 72.0% for direct LED-FM (P = 0.06) and direct ZN (P = 0.06), respectively. Specificity was 87.8% for LED-FM after NaOCl sedimentation compared to 96.7% and 95.9% for direct LED-FM (P<0.01) and direct ZN (P<0.01), respectively. Inter-reading agreement (kappa = 0.7) and technicians' acceptability were good.
NaOCl sedimentation did not improve the performance of LED-FM in the diagnosis of pulmonary TB at peripheral health service level.
在资源匮乏国家的基层卫生服务机构，痰涂片显微镜检查是唯一可用的结核病（TB）诊断方法。在高 HIV 流行地区，其敏感性会降低。在显微镜检查之前使用次氯酸钠（NaOCl）标本沉淀和发光二极管（LED）-荧光显微镜（FM）可以分别提高显微镜检查的性能。本研究旨在评估基层卫生服务中联合使用 LED-FM 和 NaOCl 痰沉淀进行 TB 检测的性能。
在肯尼亚内罗毕的一个城市卫生诊所进行了一项前瞻性研究。连续两天从疑似结核病患者中采集了 3 份痰标本。制备涂片并用金胺 O 和齐氏染色（ZN）方法染色。将剩余标本加入 3.5%的漂白剂，在室温下过夜沉淀。在沉淀的涂片上进行金胺 O 染色。采集第 4 份标本进行 TB 培养。在与 ZN 涂片相同的显微镜下读取金胺涂片，但配备了 LED FluoLED™荧光照明器。
共纳入 497 例患者，采集了 1394 份标本。与直接 LED-FM（20.6%）和直接 ZN（20.3%）相比，经 NaOCl 沉淀后，阳性标本的检出率显著增加（24.9%）。在检测涂阳患者方面，经 NaOCl 沉淀后的 LED-FM 敏感性为 78.5%，而直接 LED-FM 分别为 73.2%和 72.0%（P=0.06）和直接 ZN（P=0.06）。经 NaOCl 沉淀后的 LED-FM 特异性为 87.8%，而直接 LED-FM 分别为 96.7%和 95.9%（P<0.01）和直接 ZN（P<0.01）。两次阅读的一致性（kappa=0.7）和技术员的可接受性良好。
在基层卫生服务水平，NaOCl 沉淀并未改善 LED-FM 对肺结核的诊断性能。
