Department of Dermatology and Allergy, University of Bonn, Bonn, Germany.
J Eur Acad Dermatol Venereol. 2011 Feb;25(2):235-7. doi: 10.1111/j.1468-3083.2010.03704.x. Epub 2010 May 7.
Onychomycosis is a common problem. Today, the gold standard in the diagnosis of onychomycosis is the direct microscopy and fungal culture. But direct microscopy is regarded as having a low sensitivity and fungal culture takes long time. In addition, in cases of controlling the antifungal treatment course, the present gold standard is often not a reliable tool because of the inhibition of the fungal growth in the culture.
The purpose of this study was to compare the present gold standard with histological examination with periodic acid-Schiff staining (PAS) of nail clippings in the diagnosis of onychomycosis in a large cohort.
We prospectively evaluated 1146 nail samples from 851 patients with clinical signs of onychomycosis using direct microscopy and fungal culture in comparison with PAS-stain.
A total of 631 nail samples revealed a positive result in at least one test. The most sensitive single test for the diagnosis of onychomycosis was PAS with 82%, followed by culture (53%) and direct microscopy (48%). In 64 cases, in which a prediagnostic antimycotic treatment has been initiated, PAS showed to have by far the highest sensitivity (88%) in comparison with culture (33%) or direct microscopy (50%).
Periodic acid-Schiff staining is the single method with the highest sensitivity in terms of detection of fungal elements (hyphae) in nail specimens. Especially in cases with prior antifungal treatment, histological analysis of PAS-stained nail clippings should be considered as an appropriate diagnostic tool.
甲真菌病是一种常见的问题。目前,甲真菌病的金标准诊断方法是直接显微镜检查和真菌培养。但是,直接显微镜检查的灵敏度较低,真菌培养需要很长时间。此外,在控制抗真菌治疗过程中,由于培养物中真菌生长受到抑制,目前的金标准往往不是可靠的工具。
本研究的目的是比较直接显微镜检查和真菌培养与指甲剪片过碘酸雪夫染色(PAS)在诊断大样本甲真菌病中的表现。
我们前瞻性地评估了 851 例有甲真菌病临床体征的患者的 1146 个指甲样本,分别采用直接显微镜检查和真菌培养,并与 PAS 染色进行比较。
共有 631 个指甲样本在至少一项检查中呈阳性。PAS 对甲真菌病的诊断最敏感,为 82%,其次是培养(53%)和直接显微镜检查(48%)。在 64 例预先进行抗真菌治疗的病例中,PAS 的敏感性(88%)明显高于培养(33%)或直接显微镜检查(50%)。
PAS 是检测指甲样本中真菌成分(菌丝)的单一方法中最敏感的方法。特别是在有抗真菌治疗史的情况下,应考虑对 PAS 染色的指甲剪屑进行组织学分析作为一种合适的诊断工具。