| Abstract: | 研究目的 : 本研究目的在臨床常規應用BDProbeTEC ET系統(Becton Dickinson, Sparks, Md.)做為快速分子診斷方法，來鑑定肺部及肺外部檢體的結核分枝桿菌感染。
研究方法及設計 : 本研究從2002年8月到2005年3月，在中山醫學大學附設醫院，總共從248位臨床疑似結核病之病患，收集的380個肺部及肺部外檢體做分析。比較快速分子診斷方法、傳統的抗酸性染色法與結核分枝桿菌培養之敏感性、特異性、陽性預測值及陰性預測值。
結果 : 所收集的380個肺部及肺部外檢體中，有278個檢體做快速分子診斷方法，其中快速分子診斷方法從54個培養為結核分枝桿菌檢體中偵測37個檢體為陽性，陽性率為68.5%，從224個培養為陰性檢體中偵測到60個檢體為陽性，偽陽性率為26.8%。以抗酸性染色法偵測，發現陽性率為40.5%(32/72)，偽陽性率為14.3%(43/301)。若以培養結核分枝桿菌陽性為”金字標準”做比較，快速分子診斷方法之敏感性、特異性、陽性預測值及陰性預測值分別為68.5%、73.2%、38.1%、及90.6%。若以痰液檢體做分析快速分子診斷方法之敏感性為68.5%，比抗酸性染色法敏感性40.5%高(p值<0.05)。在144個肺部外檢體中做快速分子診斷方法，其中快速分子診斷方法從7個培養為結核分枝桿菌檢體中偵測5個檢體為陽性，陽性率為71.4%，從137個培養為陰性檢體中偵測到28個檢體為陽性，偽陽性率為20.4%，若以培養結核分枝桿菌陽性為”金字標準”做比較，快速分子診斷方法之敏感性、特異性、陽性預測值及陰性預測值分別為71.4%、79.6%、15.2%、及98.2%。以快速分子診斷方法檢測非呼吸道檢體的敏感性低，其敏感性在肋膜液、腦脊髓液及早晨尿液檢體的分別為60%，100%和100%。在於此研究中抗酸性染色法陽性的檢體，快速分子診斷方法的敏感性是高的，81.8%於單一痰液檢體，100%於支氣管肺泡沖洗術所得的檢體，對抗酸性染色法陰性測試的敏感性是低的，66.7%於單一痰液檢體，45.5%於支氣管肺泡沖洗術所得的檢體。
結論 : 從研究結果發現快速分子診斷方法為快速及有用診斷方法、但對於抗酸性染色法陰性檢體做比較、快速分子診斷方法之敏感性仍然太低、所以快速分子診斷方法仍然不足以單用來診斷結核病。對於抗酸性染色法抹片陰性之病患，必須配合流行病之資料、病患之臨床表現、影像學變化及培養做為診斷結核病之條件。
Study objectives: To determine the usefulness of the BDProbeTEC ET (Becton Dickinson) Mycobacterium tuberculosis (M. tuberculosis) complex direct detection assay (DTB), acid-fast bacillus (AFB) staining, and culture for the routine detection of M. tuberculosis in respiratory and nonrespiratory specimens in a clinical setting.
Design and setting: Prospective analysis of clinical and laboratory data in patients with suspected TB at Chung Shan Medical University Hospital (Taichung, Taiwan) from August 2000 to March 2005. A total of 380 respiratory and nonrespiratory specimens from 248 patients with suspected TB were analyzed using AFB smear, culture, and DTB.
Results: DTB was performed in 278 specimens and was positive in 37 of 54 (68.5%) culture-positive and 60 of 224 (26.8%) culture-negative specimens. AFB was positive in 32 of 79 (40.5%) culture-positive and 43 of 301 (14.3%) culture-negative specimens. When compared with culture (“gold standard”), DTB sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were 68.5%, 73.2%, 38.1%, and 90.6%, respectively. The sensitivity of a single DTB assay (68.5%) was better than AFB smear (40.5%) (P<0.05). Of 144 nonrespiratory specimens, DTB was positive in 5 of 7 (71.4%) culture-positive and 28 of 137 (20.4%) culture-negative specimens. Compared with culture, DTB sensitivity, specificity, PPV, and NPV in non-respiratory specimens were 71.4%, 79.6%, 15.2%, and 98.2%, respectively, although DTB sensitivity ranged from 60%-100% in different specimens. DTB sensitivity was high for smear-positive sputum (81.8%) and bronchoalveolar lavage(BAL) specimens (100%), but was low with smear-negative sputum (66.7%) and BAL (45.5%) specimens.
Conclusions: DTB assay offers an alternative method for direct detection of M. tuberculosis in respiratory and nonrespiratory specimens. DTB assay alone is insufficient as a single diagnostic method for diagnosis of TB. Clinical diagnosis remains the ultimate decision in the management of TB, especially in smear-negative patients. In smear-negative patient, epidemiological data, clinical symptoms and signs, radiological manifestations, and the patient’s response to empirical treatment are the criteria for diagnosis of TB. |
