Lawson L, Yassin M A, Ramsay A, Olajide I, Thacher T D, Davies P D O, Squire S B, Cuevas L E
Zankli Medical Centre, Plot 1021, B5 Shehu Yar'adua Way, Abuja, Nigeria, and Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA, UK.
Tuberculosis (Edinb). 2006 Jan;86(1):34-40. doi: 10.1016/j.tube.2005.06.003. Epub 2005 Nov 2.
Smear microscopy is relatively insensitive for the diagnosis of TB. The digestion of sputum with household bleach prior to smear preparation has been reported to improve its sensitivity. This method has not been validated.
Seven hundred and fifty six patients with symptoms suggestive of pulmonary TB (PTB) were asked to submit 3 sputum specimens for direct microscopy. One specimen was selected at random for culture and another specimen was digested to prepare a further smear. The WHO case definition (>or=2 positive smears or one positive smear and positive culture) was used to compare the sensitivity and specificity of the smears.
Four hundred and fifty five (60%) patients were culture-positive. Of these, 235 (31%) had "definite" PTB and 223 (29%) "very likely" PTB (smear-negative, culture-positive). The WHO case definition identified 51% (235/458) of the patients with "definite" or "very likely" PTB. One digested smear detected 219 (93%) of the 235 patients with "definite" PTB and 10 patients with "very likely" PTB (sensitivity (95%CI) 50% (45-55%); specificity 99% (97-100%)). The positive and negative predictive values for one digested smear were 98% (95-99%) and 56% (52-60%) respectively, which were not different (p>0.5) to the WHO case definition (100% and 57%, respectively).
One bleach-digested smear is as sensitive and specific as the WHO case definition for the diagnosis of PTB.
涂片显微镜检查对结核病的诊断相对不敏感。据报道，在制备涂片前用家用漂白剂消化痰液可提高其敏感性。但该方法尚未得到验证。
756例有肺结核（PTB）症状的患者被要求提交3份痰标本用于直接显微镜检查。随机选择一份标本进行培养，另一份标本进行消化以制备进一步的涂片。采用世界卫生组织的病例定义（≥2份涂片阳性或1份涂片阳性且培养阳性）来比较涂片的敏感性和特异性。
455例（60%）患者培养阳性。其中，235例（31%）患有“确诊”PTB，223例（29%）患有“很可能”PTB（涂片阴性，培养阳性）。世界卫生组织的病例定义识别出51%（235/458）的“确诊”或“很可能”PTB患者。一份消化后的涂片检测出235例“确诊”PTB患者中的219例（93%）和10例“很可能”PTB患者（敏感性（95%CI）50%（45 - 55%）；特异性99%（97 - 100%））。一份消化后涂片的阳性预测值和阴性预测值分别为98%（95 - 99%）和56%（52 - 60%），与世界卫生组织的病例定义（分别为100%和57%）无差异（p>0.5）。
对于PTB的诊断，一份经漂白剂消化后的涂片与世界卫生组织的病例定义一样敏感和特异。
