Introduction

Onychomycosis is a frequent and underdiagnosed condition. Approximately 90% of toenail onychomycosis infections are caused by dermatophytes, but classical diagnosis based on culture and microscopy observation is slow and has low sensitivity. Both limitations can be solved incorporating molecular techniques to routine diagnosis of onychomycosis.

Objective

Prospective evaluation of the utility of incorporating in the clinical laboratory workflow a commercial real time PCR (qPCR) for dermatophytes detection in nails after potassium hydroxide direct observation screening.

Materials and methods

152 nail samples were included (34 KOH negative and 118 KOH positive) and processed by culture and qPCR.

Results

In the negative KOH group, only one dermatophyte grew in culture and three were detected by qPCR. In the group of positive KOH, 57 dermatophytes grew in culture and 81 were detected by qPCR. In this group, 25% of diagnosed dermatophytes were detected only by qPCR. The sensitivity of qPCR compared to culture is 92.8% and time of response decreases from days to hours.

Conclusion

Based in our results, we propose a workflow algorithm for a clinical laboratory that eliminates culture for qPCR positive samples.

中文翻译：

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用于快速诊断甲真菌病的商业实时 PCR 实施：临床实验室中的新工作流程

介绍

灰指甲是一种常见且诊断不足的疾病。大约 90% 的脚趾甲灰指甲感染是由皮肤癣菌引起的，但基于培养和显微镜观察的经典诊断缓慢且敏感性低。将分子技术结合到甲真菌病的常规诊断中可以解决这两个限制。

客观的

对在临床实验室工作流程中加入商业实时 PCR (qPCR) 的效用进行前瞻性评估，用于在氢氧化钾直接观察筛选后检测指甲中的皮肤癣菌。

材料和方法

包括 152 个指甲样本（34 个 KOH 阴性和 118 个 KOH 阳性）并通过培养和 qPCR 进行处理。

结果

在阴性 KOH 组中，仅一种皮肤癣菌在培养中生长，qPCR 检测到 3 种。KOH阳性组57株皮肤癣菌生长，qPCR检测81株。在该组中，25% 的确诊皮肤癣菌仅通过 qPCR 检测到。与培养相比，qPCR 的灵敏度为 92.8%，响应时间从几天缩短到几小时。

结论

根据我们的结果，我们为临床实验室提出了一种工作流程算法，该算法消除了 qPCR 阳性样本的培养。