Reisberger E-M, Abels C, Landthaler M, Szeimies R-M
Department of Dermatology, University of Regensburg, Franz-Josef-Strauss-Allee 11, 93042 Regensburg, Germany.
Br J Dermatol. 2003 Apr;148(4):749-54. doi: 10.1046/j.1365-2133.2003.05029.x.
The current laboratory methods for diagnosing fungal infections of the nails are the potassium hydroxide (KOH) scraping technique and fungal culture. However, due to the long incubation period required for fungal culture and the reported rate of approximately 30% false negative results observed when using these methods, a quick and highly specific screening test for diagnosing onychomycosis is urgently needed.
In a prospective study, to compare the traditional mycological diagnostics using culture medium and KOH preparation with the histopathological diagnosis of onychomycosis by periodic acid-Schiff (PAS)-stained nail clippings.
Material from 387 nails of 350 patients suspected of having onychomycosis was obtained and a KOH stain as well as two fungal cultures (Kimmig agar with and without cycloheximide) were prepared. In addition, the same specimen was histopathologically examined (PAS stain).
Culture medium and KOH preparation respectively revealed 100 and 156 cases of onychomycosis, as compared with 182 cases by histological examination. Histological examination gave a significantly higher rate of positive results (P < 0.05). Considering the total number of positive results given by at least one of the three methods (total = 438), histological evaluation was found to give the highest rate of successful recognition of mycotic infection (41.6%).
The histopathological evaluation of PAS-stained nail clippings is very quick and easy to perform, and will increase the frequency of diagnosing onychomycotic disease above that achieved by culture and KOH preparation alone. However, because information concerning the vitality of the fungi and accurate identification of the specific pathogen is not available through this investigation alone, mycological culture continues to remain the indisputable 'gold standard' of mycological diagnostics.
目前用于诊断指甲真菌感染的实验室方法是氢氧化钾（KOH）刮片技术和真菌培养。然而，由于真菌培养所需的孵育期较长，且使用这些方法时报告的假阴性结果率约为30%，因此迫切需要一种快速且高度特异的筛查试验来诊断甲癣。
在一项前瞻性研究中，比较使用培养基和KOH制剂的传统真菌学诊断与通过过碘酸希夫（PAS）染色的指甲剪进行甲癣组织病理学诊断的结果。
获取了350例疑似甲癣患者的387个指甲样本，进行了KOH染色以及两种真菌培养（含和不含环己酰亚胺的金米格琼脂）。此外，对相同样本进行了组织病理学检查（PAS染色）。
培养基和KOH制剂分别检测出100例和156例甲癣，而组织学检查发现182例。组织学检查的阳性结果率显著更高（P < 0.05）。考虑到三种方法中至少一种给出的阳性结果总数（总计 = 438），发现组织学评估对真菌感染的成功识别率最高（41.6%）。
PAS染色指甲剪的组织病理学评估操作非常快速且简便，与单独使用培养和KOH制剂相比，将提高甲癣疾病的诊断频率。然而，由于仅通过此项检查无法获得有关真菌活力的信息以及特定病原体的准确鉴定结果，真菌培养仍然是真菌学诊断无可争议的“金标准”。
