Department of Biochemistry, Institute of Post Graduate Medical Education and Research, Kolkata, West Bengal, India.
Indian J Dermatol Venereol Leprol. 2013 Sep-Oct;79(5):693-700. doi: 10.4103/0378-6323.116740.
Leprosy is not always an easy disease to diagnose, and patients can remain undiagnosed for longtime, not only at the peripheral clinics but also even at places with higher medical facilities, so, there is an urgent need for rapid and definitive modalities for leprosy diagnosis. This prospective study evaluates the ability of Fite-Faraco staining (FF staining) and multiplex polymerase chain reaction (PCR) over hematoxylin and eosin staining (H and E staining) and Ziehl-Neelsen staining (ZN staining).
The aim of this perspective study is to evaluate the effectiveness of FF staining in combination with multiplex PCR for the early and rapid diagnosis of leprosy than any other coexisting diagnosis tool.
Patients with new skin patches or nodules with or without evidence of nerve damage were selected for the study. Punch biopsy was collected according to standard procedures. Each biopsy sample was divided into two equal parts, one half was fixed in 4% (v/v) buffered neutral formalin and then accordingly embedded in paraffin. Sections were stained by three different methods: H and E staining for histopathological examination, ZN staining, and FF staining for detection of acid-fast bacilli (AFB). And the other part was subjected for DNA extraction and PCR was carried out by the obtained DNA sample.
H and E staining, ZN staining, FF staining, and PCR yield 58.2%, 50.9%, 60%, and 67.7% successful diagnosis of leprosy. The true diagnostic performances for these techniques were as follows: H and E staining - sensitivity 70.6%, positive predictive value (PPV) 81.9%, negative predictive value (NPV) 53.6%. For ZN staining - sensitivity 59.9%, PPV 69%, NPV 45.7%. For FF staining - sensitivity 74.6%, PPV 85.9%, NPV 56.7%, and for PCR - sensitivity 87.8%, PPV 95.6%, NPV 71.2%.
The combination of FF staining and PCR was shown to provide a rapid and definitive diagnosis in the majority of leprosy suspected cases with a higher positive likelihood ratio (+LR) of 7.76 and 2.716, respectively, than H and E staining of 2.244 and ZN staining of 1.378.
麻风病的诊断并不总是那么容易，患者可能会长期得不到诊断，不仅在基层诊所，甚至在医疗设施较高的地方也是如此，因此，迫切需要快速、明确的麻风病诊断方法。本前瞻性研究评估了 Fite-Faraco 染色（FF 染色）和多重聚合酶链反应（PCR）与苏木精和伊红染色（H&E 染色）和齐-尼染色（ZN 染色）相比在麻风病诊断中的能力。
本研究旨在评估 FF 染色联合多重 PCR 在早期快速诊断麻风病方面的有效性，优于其他现有诊断工具。
选择有新皮肤斑块或结节的患者，这些结节有或没有神经损伤的证据。按照标准程序采集打孔活检。每个活检样本被分成两个相等的部分，一半固定在 4%（v/v）缓冲中性福尔马林溶液中，然后相应地包埋在石蜡中。使用三种不同的方法对切片进行染色：H&E 染色用于组织病理学检查，ZN 染色和 FF 染色用于检测抗酸杆菌（AFB）。另一半用于 DNA 提取，并用提取的 DNA 样本进行 PCR。
H&E 染色、ZN 染色、FF 染色和 PCR 分别成功诊断麻风病 58.2%、50.9%、60%和 67.7%。这些技术的真实诊断性能如下：H&E 染色-灵敏度 70.6%，阳性预测值（PPV）81.9%，阴性预测值（NPV）53.6%。ZN 染色-灵敏度 59.9%，PPV 69%，NPV 45.7%。FF 染色-灵敏度 74.6%，PPV 85.9%，NPV 56.7%，PCR-灵敏度 87.8%，PPV 95.6%，NPV 71.2%。
FF 染色和 PCR 的联合应用在大多数疑似麻风病患者中提供了快速、明确的诊断，与 H&E 染色的阳性似然比（+LR）为 2.244，ZN 染色的为 1.378相比，其阳性似然比（+LR）分别为 7.76 和 2.716。
