應用核酸擴增技術診斷結核病

Nucleic Acid Amplification Tests for the Diagnosis of Tuberculosis

診斷結核病需整合多種檢測工具，各種方法皆具有其優勢與限制，尚無單一檢測方式能完全滿足所有臨床需求。對於菌量較低、免疫功能低下，以及肺外結核病人而言，診斷延遲尤其常見。傳統痰抗酸性塗片（acid-fast stain，AFS）檢查敏感度有限，加上結核菌培養所需時間較長，更突顯快速且準確之分子診斷工具的必要性。新型核酸擴增技術（nucleic acid amplification tests，NAATs）具有高度特異性，能顯著縮短診斷及治療啟動所需時間，對於抗酸菌塗片陰性病人尤具臨床價值。然而，聚合酶鏈反應（polymerase chain reaction，PCR）的診斷效能，易受檢體種類及實驗室操作流程影響，因此其敏感度與特異性於不同研究及臨床環境間，存在相當大的差異。此外，PCR無法區分存活菌與死亡菌，因此仍無法取代結核菌培養及完整的藥物敏感性試驗。在臨床實務與公共衛生應用上，採用多元整合的診斷策略至關重要。診斷方法的選擇，應依據病人個別因素，包括菌量、免疫狀態及檢體種類，並同時考量醫療資源的可近性。透過將結核菌培養與核酸擴增檢測，包括：Xpert平台、PCR及線性探針試驗（line probe assay，LPA）的早期應用相互結合，不僅可提升診斷效能，亦能支持及時且精確的治療決策，同時保有藥物抗藥性評估的能力。

Diagnosis of tuberculosis (TB) relies on a variety of tools, each with its own strengths and limitations, and no single method can fully meet all clinical needs. Diagnostic delays are particularly common in patients with low bacillary burden, immunocompromised individuals, and those with extrapulmonary TB. The limited sensitivity of conventional acid-fast stain (AFS) and the prolonged turnaround time of culture further highlight the need for rapid and accurate molecular diagnostic tools. Nucleic acid amplification tests (NAATs) offer high specificity and significantly shorten the time to diagnosis and treatment initiation, demonstrating the clinical value particularly in patients with smear-negative results. However, the performance of polymerase chain reaction (PCR) is influenced by specimen type and laboratory procedures, leading to considerable variability in sensitivity and specificity across different settings. In addition, PCR cannot distinguish between viable and nonviable organisms and therefore cannot replace culture and comprehensive drug susceptibility testing. In clinical practice and public health applications, a multimodal diagnostic approach is essential. The selection of appropriate diagnostic methods should be guided by patient-specific factors—such as bacillary load, immune status, and specimen type—as well as available healthcare resources. By integrating culture with early use of NAATs (including Xpert platforms, PCR, and line probe assays), it is possible to improve diagnostic performance and support timely treatment decisions while maintaining the ability to assess drug resistance.