Kam K M, Yip C W, Tang H S, Van Deun A
TB Reference Laboratory, Public Health Laboratory Services Branch, Centre for Health Protection, Department of Health, Hong Kong, China.
Int J Tuberc Lung Dis. 2009 Sep;13(9):1119-23.
A high-throughput laboratory routinely performing fluorescence microscopy for acid-fast bacilli (AFB) smear with automated bulk staining.
To determine the risk of false-positive AFB sputum smears from bulk staining showing as smear-positive, culture-negative specimens, or a decrease in smear- and culture-positives.
Direct AFB smear and Löwenstein-Jensen culture were performed for a total of 39,350 routine sputum specimens. Of these, 6633 were randomly selected for individual AFB staining, while the remaining 32,717 were processed by bulk machine staining. Positives for smear and culture were compared.
Overall, 111 specimens yielded a positive individually stained smear; of these, 100 (90.1%, 95%CI 83.0-95.0) were also culture-positive compared to 504/543 smear-positives after bulk staining (92.8%, 95%CI 90.6-95.0). The proportions of smear-positive, culture-negative and smear- and culture-positive specimens were respectively 1.8% vs. 2.2% and 90.1% vs. 92.8%, for individual and bulk staining (non-significant).
The risk of transferring AFB from positive to negative smears during bulk AFB staining is negligible, if it occurs at all. Bulk staining should not be discouraged, as even in low-income countries this method will save significant resources, particularly manpower, and improve staining results in laboratories with a high workload.
一个高通量实验室常规使用自动批量染色法进行抗酸杆菌（AFB）涂片的荧光显微镜检查。
确定批量染色导致痰涂片AFB假阳性的风险，即涂片阳性但培养阴性的标本，或涂片和培养阳性率的降低。
对总共39350份常规痰标本进行直接AFB涂片和罗氏培养基培养。其中，6633份被随机选择进行个体AFB染色，其余32717份通过批量机器染色处理。比较涂片和培养的阳性结果。
总体而言，111份标本个体染色涂片呈阳性；其中，100份（90.1%，95%CI 83.0 - 95.0）培养也呈阳性，相比之下，批量染色后543份涂片阳性标本中有504份（92.8%，95%CI 90.6 - 95.0）培养呈阳性。个体染色和批量染色的涂片阳性、培养阴性以及涂片和培养均阳性标本的比例分别为1.8%对2.2%和90.1%对92.8%（无显著差异）。
在批量AFB染色过程中，AFB从阳性涂片转移到阴性涂片的风险（如果确实存在）可以忽略不计。不应阻碍批量染色，因为即使在低收入国家，这种方法也将节省大量资源，特别是人力，并改善工作量大的实验室的染色结果。
