Bonnet Maryline, Ramsay Andrew, Githui Willie, Gagnidze Laramie, Varaine Francis, Guerin Philippe J
Epicentre, Paris, France.
Clin Infect Dis. 2008 Jun 1;46(11):1710-6. doi: 10.1086/587891.
The purpose of the study was to evaluate the performance and feasibility of tuberculosis diagnosis by sputum microscopy after bleach sedimentation, compared with by conventional direct smear microscopy, in a setting of high prevalence of HIV.
In a community-based study in Kenya (a population in which 50% of individuals with tuberculosis are infected with HIV), individuals with suspected pulmonary tuberculosis submitted 3 sputum specimens during 2 consecutive days, which were examined by blind evaluation. Ziehl-Neelsen-stained smears were made of fresh specimens and of specimens that were processed with 3.5% household bleach followed by overnight sedimentation. Two different cutoffs for acid-fast bacilli (AFB) per 100 high-power fields (HPF) were used to define a positive smear: >10 AFB/100 HPF and 1 AFB/100 HPF. Four smear-positive case definitions, based on 1 or 2 positive smears with the 1 AFB or 10 AFB cutoff, were used.
Of 1879 specimens from 644 patients, 363 (19.3%) and 460 (24.5%) were positive by bleach sedimentation microscopy, compared with 301 (16.0%) and 374 (19.9%) by direct smear microscopy, with use of the 10 AFB/100 HPF (P < .001) and 1 AFB/100 HPF (P < .001) cutoffs, respectively. Regardless of the case definition used, bleach sedimentation microscopy detected significantly more positive cases than did direct smear microscopy: 26.7% (172 of 644) versus 21.7% (140 of 644), respectively, with the case definition of 1 positive smear and the 1 AFB/100 HPF cutoff (P < .001), and 21.4% (138 of 644) versus 18.6% (120 of 644), respectively, with the case definition of 1 positive smear and the 10 AFB/100 HPF cutoff (P < .001). Inter- and intrareader reproducibility were favorable, with kappa coefficients of 0.83 and 0.91, respectively. Bleach sedimentation was relatively inexpensive and was not time consuming.
Bleach sedimentation microscopy is an effective, simple method to improve the yield of smear microscopy in a setting of high prevalence of HIV. Further evaluation of this method, under operational conditions, is urgently needed to determine its potential as a tool for tuberculosis control.
本研究的目的是在艾滋病毒高流行环境中，评估经漂白剂沉淀后的痰涂片显微镜检查用于结核病诊断的性能和可行性，并与传统直接涂片显微镜检查进行比较。
在肯尼亚开展的一项基于社区的研究（该人群中50%的结核病患者感染了艾滋病毒）中，疑似肺结核患者连续两天提交3份痰标本，由专人进行盲法评估。对新鲜标本以及用3.5%家用漂白剂处理过夜后沉淀的标本制作萋-尼染色涂片。每100个高倍视野（HPF）中抗酸杆菌（AFB）的两个不同截断值用于定义涂片阳性：>10条AFB/100 HPF和1条AFB/100 HPF。基于1条或2条阳性涂片以及1条AFB或10条AFB截断值，使用了四种涂片阳性病例定义。
在来自644例患者的1879份标本中，采用10条AFB/100 HPF截断值时，经漂白剂沉淀显微镜检查阳性的标本分别为363份（19.3%）和460份（24.5%），而直接涂片显微镜检查阳性的标本分别为301份（16.0%）和374份（19.9%）（P <.001）；采用1条AFB/100 HPF截断值时，结果分别为363份（19.3%）和460份（24.5%）以及301份（16.0%）和374份（19.9%）（P <.001）。无论使用哪种病例定义，漂白剂沉淀显微镜检查检测到的阳性病例均显著多于直接涂片显微镜检查：分别为26.7%（644例中的172例）和21.7%（644例中的140例），病例定义为1条阳性涂片且截断值为1条AFB/100 HPF（P <.001）；分别为21.4%（644例中的138例）和18.6%（644例中的120例），病例定义为1条阳性涂片且截断值为10条AFB/100 HPF（P <.001）。阅片者间和阅片者内的重复性良好，kappa系数分别为0.83和0.91。漂白剂沉淀相对便宜且不耗时。
在艾滋病毒高流行环境中，漂白剂沉淀显微镜检查是一种提高涂片显微镜检查阳性率的有效、简便方法。迫切需要在实际操作条件下对该方法进行进一步评估，以确定其作为结核病控制工具的潜力。
