Ginesu F, Pirina P, Sechi L A, Molicotti P, Santoru L, Porcu L, Fois A, Arghittu P, Zanetti S, Fadda G
Institute of Respiratory Diseases, University of Sassari, Italy.
J Chemother. 1998 Aug;10(4):295-300. doi: 10.1179/joc.1998.10.4.295.
The aim of our study was to evaluate the diagnostic value of various methods widely used in microbiological diagnosis of tuberculosis: direct smear examination for acid-fast bacilli, cultural identification in Lowestein-Jensen (L-J) medium, the radiometric BACTEC 460 system, and Polymerase Chain Reaction (PCR). Three hundred and ninety-three clinical samples of sputum (375), gastric aspirate (3), pleural fluid (12) and urine (3) were taken from 125 patients hospitalized at our Institute for suspected pulmonary tuberculosis, between January 1995 and June 1997. On completion of diagnosis, 35 were found to be affected by active tuberculosis (30 pulmonary, 4 pleural and 1 urinary) and 90 by other non-tubercular diseases (pneumonia, lung cancer, non-tubercular pleural effusion, etc.). In our study, direct smear examination for acid-smear bacilli gave diagnostic value results of 88% and positive predictive value of 91.67%. Cultural identification in L-J and BACTEC 460 TB radiometric system media resulted in diagnostic values of 96.80% and 94.40%, respectively, and positive predictive values of 100% for both of them. Finally, One-Tube Nested-PCR, a variant which uses specific primers for the IS6110 insertion sequence specific for Mycobacterium tuberculosis, gave us 88.80% (91.43% sensitivity and 87.78% specificity) diagnostic value results, and 74.42% (11 false-positives) positive predictive value. On the basis of our results, we can affirm that PCR is a good method for microbiological diagnosis of tuberculosis, given its high sensitivity and specificity and unparalleled rapidity. However, the high number of false-positives that we found suggests that results obtained should be confirmed with BACTEC, which considerably reduces the time required for identification, and makes it possible to carry out an antibiotic assay rapidly.
抗酸杆菌直接涂片检查、在罗-琴（L-J）培养基上进行培养鉴定、放射性BACTEC 460系统以及聚合酶链反应（PCR）。1995年1月至1997年6月期间，从我院收治的125例疑似肺结核住院患者中采集了393份临床样本，包括痰液（375份）、胃抽吸物（3份）、胸腔积液（12份）和尿液（3份）。诊断完成后，发现35例患有活动性结核病（30例肺部、4例胸膜和1例泌尿系统），90例患有其他非结核性疾病（肺炎、肺癌、非结核性胸腔积液等）。在我们的研究中，抗酸涂片杆菌直接涂片检查的诊断价值结果为88%，阳性预测值为91.67%。在L-J和BACTEC 460 TB放射性系统培养基上进行培养鉴定的诊断价值分别为96.80%和94.40%，两者的阳性预测值均为100%。最后，单管巢式PCR（一种使用针对结核分枝杆菌特异性IS6110插入序列的特异性引物的变体）的诊断价值结果为88.80%（敏感性为91.43%，特异性为87.78%），阳性预测值为74.42%（11例假阳性）。根据我们的结果，我们可以肯定，鉴于其高敏感性、特异性和无与伦比的快速性，PCR是结核病微生物诊断的一种好方法。然而，我们发现的假阳性数量较多表明，所获得的结果应该用BACTEC进行确认，这大大减少了鉴定所需的时间，并使得能够快速进行抗生素检测。
