Pospischil Isabella, Reinhardt Charlotte, Bontems Olympia, Salamin Karine, Fratti Marina, Blanchard Gabriela, Chang Yun-Tsan, Wagner Helga, Hermann Philipp, Monod Michel, Hoetzenecker Wolfram, Guenova Emmanuella
Department of Dermatology, Kepler University Hospital, Johannes Kepler University Linz, 4020 Linz, Austria.
Department of Dermatology, Lausanne University Hospital (CHUV) and the Faculty of Biology and Medicine, University of Lausanne, 1007 Lausanne, Switzerland.
J Fungi (Basel). 2022 Sep 27;8(10):1019. doi: 10.3390/jof8101019.
Rapid and reliable fungal identification is crucial to delineate infectious diseases, and to establish appropriate treatment for onychomycosis. Compared to conventional diagnostic methods, molecular techniques are faster and feature higher accuracy in fungal identification. However, in current clinical practice, molecular mycology is not widely available, and its practical applicability is still under discussion. This study summarizes the results of 16,094 consecutive nail specimens with clinical suspicion of onychomycosis. We performed PCR/sequencing on all primary nail specimens for which conventional mycological diagnostics remained inconclusive. In specimens with a positive direct microscopy but negative or contaminated culture, molecular mycology proved superior and specified a fungal agent in 65% (587/898). In 75% (443/587), the identified pathogen was a dermatophyte. Positive cultures for dermatophytes, yeasts and non-dermatophyte molds (NDMs) were concordant with primary-specimen-DNA PCR/sequencing in 83% (10/12), 34% (22/65) and 45% (76/169), respectively. Among NDMs, agreement was high for spp. (32/40; 80%), but low for spp. (5/25; 20%) and spp. (1/20; 5%). This study underlines the improvement in diagnostic yield by fungal primary-specimen-DNA PCR/sequencing in the event of a negative or contaminated culture, as well as its significance for the diagnosis of dermatophyte and non-dermatophyte onychomycosis. Molecular mycology methods like PCR and DNA sequencing should complement conventional diagnostics in cases of equivocal findings, suspected NDM onychomycosis or treatment-resistant nail pathologies.
快速可靠的真菌鉴定对于明确感染性疾病以及确定甲癣的适当治疗方法至关重要。与传统诊断方法相比，分子技术在真菌鉴定方面速度更快且准确性更高。然而，在当前临床实践中，分子真菌学尚未广泛应用，其实际适用性仍在讨论中。本研究总结了16094例临床怀疑甲癣的连续指甲标本的结果。对于所有传统真菌学诊断仍不明确的原发性指甲标本，我们进行了PCR/测序。在直接显微镜检查阳性但培养阴性或污染的标本中，分子真菌学被证明更具优势，在65%（587/898）的标本中确定了真菌病原体。在75%（443/587）的标本中，鉴定出的病原体为皮肤癣菌。皮肤癣菌、酵母菌和非皮肤癣菌霉菌（NDMs）的阳性培养结果与原发性标本DNA PCR/测序的一致性分别为83%（10/12）、34%（22/65）和45%（76/169）。在NDMs中， spp.的一致性较高（32/40；80%），但 spp.（5/25；20%）和 spp.（1/20；5%）的一致性较低。本研究强调了在培养阴性或污染的情况下，通过真菌原发性标本DNA PCR/测序提高诊断率，以及其对皮肤癣菌和非皮肤癣菌甲癣诊断的意义。在结果不明确、怀疑NDM甲癣或治疗抵抗性指甲病变的情况下，PCR和DNA测序等分子真菌学方法应补充传统诊断方法。
