Glutaraldehyde test for the rapid diagnosis of pulmonary and extra-pulmonary tuberculosis in an area with high tuberculosis incidence

BACKGROUND Tuberculosis (TB) remains one of the leading causes of morbidity and mortality worldwide. The primary method for controlling TB is the rapid and accurate identification of infected individuals. Immune response exploitation represents one of the main methods used for early TB diagnosis; however, few studies have reported that whole blood originating from TB-infected patients gels faster in the presence of aldehyde than blood originating from healthy subjects, which is the focus of the current study. OBJECTIVES The study objectives are to determine the diagnostic value of a glutaraldehyde test (GT) in pulmonary tuberculosis (PTB) and extra-pulmonary tuberculosis (EPTB) and to assess its performance compared with light-emitting diode fluorescence microscopy (LED-FM). MATERIALS AND METHODS This study included 272 specimens (176 suspected PTB specimens and 96 suspected EPTB specimens). Of the 272 patients, 98 patients had TB infection confirmed by culture (64 PTB cases and 34 EPTB cases), and 174 patients had no TB infection. The gold standard technique (culture) was used as reference to verify the GT's performance. RESULTS The GT showed a high sensitivity (96.9%) and specificity (82.1%) for PTB with a good positive predictive value (PPV = 75.6%) and negative predictive value (NPV = 97.9%). For EPTB, the GT showed a sensitivity of 91.2% and a specificity of 77.4%, with PPV = 68.9% and NPV = 94.1%. LED-FM had lower sensitivities for PTB (65.6%) and EPTB (42.1%) and an excellent specificity of 100%, with PPV = 100% and NPV = 100%. CONCLUSION We concluded that GT is rapid, easy, simple and cost-effective and does not require qualified personnel with a specific background or sophisticated equipment like molecular biology or mycobacterium-specific genotyping techniques. These qualities make the GT attractive for use in low- and high-income countries in addition to other conventional methods, particularly culture, which continues to be the gold standard.

研究背景：结核病（Tuberculosis, TB）仍是全球范围内引发疾病与死亡的主要病因之一。结核病防控的核心手段是快速、精准地识别感染者。利用机体免疫应答是早期结核病诊断的主要方法之一；但目前鲜有研究报道，结核分枝杆菌感染者的全血在醛类物质作用下的凝胶速度快于健康受试者，本研究即围绕这一现象展开。
研究目的：本研究旨在明确戊二醛试验（glutaraldehyde test, GT）对肺结核（pulmonary tuberculosis, PTB）与肺外结核（extra-pulmonary tuberculosis, EPTB）的诊断价值，并评估其相较于发光二极管荧光显微镜（light-emitting diode fluorescence microscopy, LED-FM）的检测性能。
材料与方法：本研究共纳入272份标本，其中176份为疑似肺结核标本，96份为疑似肺外结核标本。272例受试者中，98例经培养法确认存在结核分枝杆菌感染（64例肺结核，34例肺外结核），174例未检出结核分枝杆菌感染。本研究以金标准技术（培养法）作为参照，验证戊二醛试验的检测性能。
研究结果：戊二醛试验对肺结核的检测灵敏度达96.9%，特异度达82.1%，同时具备良好的阳性预测值（positive predictive value, PPV=75.6%）与阴性预测值（negative predictive value, NPV=97.9%）。针对肺外结核，戊二醛试验的灵敏度为91.2%，特异度为77.4%，阳性预测值为68.9%，阴性预测值为94.1%。发光二极管荧光显微镜对肺结核的灵敏度为65.6%，对肺外结核的灵敏度为42.1%，但其特异度达100%，阳性预测值与阴性预测值均为100%。
研究结论：本研究结果表明，戊二醛试验操作快速简便、成本低廉，无需具备特定专业背景的检测人员，亦无需分子生物学、分枝杆菌特异性基因分型技术等复杂仪器设备。上述优势使得戊二醛试验可与其他传统检测方法（尤其是仍作为金标准的培养法）联合使用，在低收入与高收入国家均具备应用潜力。