University of Cape Town, Cape Town, South Africa.
BMC Infect Dis. 2012 Apr 26;12:103. doi: 10.1186/1471-2334-12-103.
Detection of Mycobacterium tuberculosis antigens in urine is attractive as a potential means of diagnosing tuberculosis (TB) regardless of the anatomical site of disease. The most promising candidate antigen is the cell wall lipopolysaccharide antigen lipoarabinomannan (LAM), which has been used to develop commercially available enzyme-linked immunosorbent assays. Although highly variable diagnostic accuracy has been observed in different clinical populations, it is now clear that this assay has useful sensitivity for diagnosis of HIV-associated TB in patients with advanced immunodeficiency and low CD4 cell counts. Thus, this assay is particularly useful when selectively used among patients enrolling in antiretroviral treatment services or in HIV-infected patients requiring admission to hospital medical wards. These are the very patients who have the highest mortality risk and who stand to gain the most from rapid diagnosis, permitting immediate initiation of TB treatment. A recently developed low-cost, lateral-flow (urine 'dip-stick') format of the assay provides a result within 30 minutes and is potentially a major step forward as it can be used at the point-of-care, making the possibility of immediate diagnosis and treatment a reality. This paper discusses the likely utility of this point-of-care assay and how it might best be used in combination with other diagnostic assays for TB. The many further research studies that are needed on this assay are described. Consideration is particularly given to potential reasons for the variable specificity observed in existing field evaluations of LAM ELISAs. Whether this might be related to the assay itself or to the challenges associated with study design is discussed.
检测尿液中的结核分枝杆菌抗原作为一种潜在的诊断结核病（TB）的方法很有吸引力，无论疾病的解剖部位如何。最有前途的候选抗原是细胞壁脂多糖抗原脂阿拉伯甘露聚糖（LAM），它已被用于开发商业上可用的酶联免疫吸附测定法。尽管在不同的临床人群中观察到诊断准确性高度可变，但现在很清楚，该检测法对诊断免疫功能低下和 CD4 细胞计数低的 HIV 相关结核病具有有用的敏感性。因此，当在参加抗逆转录病毒治疗服务的患者中或在需要入院接受医院内科病房治疗的 HIV 感染患者中选择性使用时，该检测法特别有用。这些正是具有最高死亡率并且最有可能从快速诊断中获益的患者，这可以立即开始进行结核病治疗。最近开发的低成本、横向流动（尿液“浸条”）检测法在 30 分钟内提供结果，这是向前迈出的重要一步，因为它可以在护理点使用，使即时诊断和治疗成为可能。本文讨论了该即时检测法的可能用途，以及如何与其他 TB 诊断检测法结合使用。还描述了该检测法所需的许多进一步研究。特别考虑了在现有 LAM ELISA 现场评估中观察到的特异性变异性的潜在原因。这是否与检测本身或与研究设计相关的挑战有关，这是值得讨论的。
