Medical School, Universidade Federal de Santa Catarina.
Braz J Infect Dis. 2010 Jan-Feb;14(1):116-20.
faster alternative techniques are required to improve the diagnosis and control of pulmonary tuberculosis.
To evaluate the sample quality in the performance of PCR for diagnosis of pulmonary tuberculosis.
during one year, sputum samples were collected from 72 pulmonary tuberculosis patients and 12 non-tuberculosis controls, which were admitted to the Nereu Ramos hospital, Florianópolis city, Brazil. The samples were subjected to Ziehl-Neelsen-stained sputum smear microscopy and Lowestein-Jensen medium culture, which were defined as gold standard tests for mycobacteria, and polymerase chain reaction (PCR). Those samples that presented more than 40% of viable cells and less than 25% of epithelial cells were defined as high quality samples.
PCR showed sensitivity of 55.6%, specificity of 41.7%, positive predictive value of 85.1%, negative predictive value of 13.5%, and accuracy of 53.6%. High quality samples showed sensitivity of 72.4%, specificity of 50%, positive predictive value of 91.3%, negative predictive value of 20%, and accuracy of 69.7%. Low quality samples showed sensitivity of 44.2%, specificity of 37.5%, positive predictive value of 79.2%, negative predictive value of 11.1%, and accuracy of 43.1%.
use of high quality samples improved significantly the PCR performance, especially on their sensitivity and positive predictive values.
需要更快的替代技术来改善肺结核的诊断和控制。
评估聚合酶链反应（PCR）诊断肺结核时的样本质量。
在一年时间内，从巴西弗洛里亚诺波利斯市 Nereu Ramos 医院收治的 72 例肺结核患者和 12 例非肺结核对照者中采集痰样本。这些样本接受了 Ziehl-Neelsen 染色痰涂片显微镜检查和 Lowestein-Jensen 培养基培养，这两种方法被定义为分枝杆菌的金标准检测，以及聚合酶链反应（PCR）。那些活细胞比例超过 40%、上皮细胞比例小于 25%的样本被定义为高质量样本。
PCR 的敏感性为 55.6%，特异性为 41.7%，阳性预测值为 85.1%，阴性预测值为 13.5%，准确性为 53.6%。高质量样本的敏感性为 72.4%，特异性为 50%，阳性预测值为 91.3%，阴性预测值为 20%，准确性为 69.7%。低质量样本的敏感性为 44.2%，特异性为 37.5%，阳性预测值为 79.2%，阴性预测值为 11.1%，准确性为 43.1%。
使用高质量样本可显著提高 PCR 的性能，尤其是敏感性和阳性预测值。
