Comparison of Fungal Culture, DermaGenius® Multiplex Real-Time PCR, and the EUROArray Dermatomycosis Assay for the Diagnosis and Species Identification of Dermatophytes

TL;DR

This study compares three methods for diagnosing fungal skin infections, finding that PCR-based tests are effective and can complement traditional culture methods.

Contribution

The study evaluates the diagnostic performance of two PCR-based assays against fungal culture for dermatophyte identification.

Findings

Both DermaGenius® and EUROArray assays showed high sensitivity in identifying dermatophyte reference strains.

PCR-based methods detected infections in culture-negative samples and unconventional species.

EUROArray showed potential false positives for F. solani, while DermaGenius® had lower clinical sample detection rates.

Abstract

Dermatophytes are fungi that infect the human skin and its appendages. With new pathogenic species emerging and resistance to first-line drugs rising, microbiologic diagnosis and species identification are becoming even more important. In this study, the DermaGenius® 2.0/3.0 Complete multiplex real-time PCR and the EUROArray Dermatomycosis kits were compared to fungal culture and with each other; 78 reference strains and 124 clinical samples were analyzed. Both the DermaGenius® kit (97%; 95%CI 89–100%) and the EUROArray assay (91%; 95% CI: 82–96%) were sensitive when analyzing on-panel reference strains. In clinical samples, the DermaGenius® assay provided a positive result in 63 out of 124 (51%) samples and the EUROArray assay in 74 out of 124 (60%) samples. Both kits supported the diagnosis and species identification of culture-negative samples, and samples with growth of unconventional species. However, there was suspicion of false-positive results with F. solani in the EUROArray kit both in clinical and reference strains. The most common conventional dermatophytes in this study combining all methods were T. rubrum/soudanense (n = 40) and T. interdigitale/mentagrophytes (n = 11). In summary, both PCR kits were sensitive for the diagnosis and species identification of dermatophytoses. Combining culture and a PCR-based method can increase the diagnostic yield and compensate for the weakness of the other methods. The optimal PCR-based kit, and especially the optimal panel size, depends on the local epidemiology of dermatophytes.

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