Laboratório de Hanseníase, Instituto Oswaldo Cruz - Fiocruz, Rio de Janeiro, Rio de Janeiro, Brazil.
Fundação Alfredo da Matta, Manaus, Amazonas, Brazil.
PLoS Negl Trop Dis. 2014 Apr 10;8(4):e2655. doi: 10.1371/journal.pntd.0002655. eCollection 2014 Apr.
In leprosy, classic diagnostic tools based on bacillary counts and histopathology have been facing hurdles, especially in distinguishing latent infection from active disease and diagnosing paucibacillary clinical forms. Serological tests and IFN-gamma releasing assays (IGRA) that employ humoral and cellular immune parameters, respectively, are also being used, but recent results indicate that quantitative PCR (qPCR) is a key technique due to its higher sensitivity and specificity. In fact, advances concerning the structure and function of the Mycobacterium leprae genome led to the development of specific PCR-based gene amplification assays for leprosy diagnosis and monitoring of household contacts. Also, based on the validation of point-of-care technologies for M. tuberculosis DNA detection, it is clear that the same advantages of rapid DNA detection could be observed in respect to leprosy. So far, PCR has proven useful in the determination of transmission routes, M. leprae viability, and drug resistance in leprosy. However, PCR has been ascertained to be especially valuable in diagnosing difficult cases like pure neural leprosy (PNL), paucibacillary (PB), and patients with atypical clinical presentation and histopathological features compatible with leprosy. Also, the detection of M. leprae DNA in different samples of the household contacts of leprosy patients is very promising. Although a positive PCR result is not sufficient to establish a causal relationship with disease outcome, quantitation provided by qPCR is clearly capable of indicating increased risk of developing the disease and could alert clinicians to follow these contacts more closely or even define rules for chemoprophylaxis.
在麻风病中，基于细菌计数和组织病理学的经典诊断工具面临着诸多挑战，尤其是在区分潜伏感染和活动性疾病以及诊断少菌型临床形式方面。目前也在使用基于体液和细胞免疫参数的血清学检测和 IFN-γ 释放检测（IGRA），但最近的结果表明，由于其更高的灵敏度和特异性，定量 PCR（qPCR）是一种关键技术。事实上，鉴于麻风分枝杆菌基因组的结构和功能方面的进展，已经开发出了针对麻风病诊断和监测家庭接触者的基于特定 PCR 的基因扩增检测方法。此外，基于对结核分枝杆菌 DNA 检测即时检测技术的验证，很明显，快速 DNA 检测的相同优势也可以在麻风病中观察到。到目前为止，PCR 已被证明可用于确定传播途径、麻风分枝杆菌的生存能力以及麻风病的耐药性。然而，PCR 已被证实对于诊断单纯神经麻风病（PNL）、少菌型（PB）以及具有与麻风病相一致的非典型临床和组织病理学特征的患者等困难病例特别有价值。此外，在麻风病患者的家庭接触者的不同样本中检测麻风分枝杆菌 DNA 也非常有前景。尽管阳性 PCR 结果不足以确立与疾病结果的因果关系，但 qPCR 的定量显然能够表明发病风险增加，从而提醒临床医生更密切地关注这些接触者，甚至可以定义化学预防规则。
