The need for fast and accurate detection of dermatomycosis

Abstract

Dermatomycosis of the hair, skin or nails are one of the most common fungal infections worldwide. Beyond permanent damage to the affected area, the risk of severe dermatomycosis in immunocompromised people can be life-threatening. The potential risk of delayed or improper treatment highlights the need for a rapid and accurate diagnosis. However, with traditional methods of fungal diagnostics such as culture, a diagnosis can take several weeks. Alternative diagnostic technologies have been developed which allow for an appropriate and timely selection of an antifungal treatment, preventing nonspecific over-the-counter self-medication. Such techniques include molecular methods such as PCR, real-time PCR, DNA microarray, next-generation sequencing, in addition to matrix-assisted laser desorption ionization–time of flight (MALDI-TOF) mass spectrometry. Molecular methods can help close the “diagnostic gap” observed with traditional cultures and microscopy and allow for a rapid detection of dermatomycosis with increased sensitivity and specificity. In this review, advantages and disadvantages of traditional and molecular techniques are discussed, in addition to the importance of species-specific dermatophyte determination. Finally, we highlight the need for clinicians to adapt molecular techniques for the rapid and reliable detection of dermatomycosis infections and to reduce adverse events. Lay Abstract Dermatomycosis is one of the most common fungal infections worldwide. Traditional fungal diagnostics are limited and can take several weeks. Molecular techniques can detect dermatomycosis pathogens quickly and allow for species-specific identification which is important for treatment.

Treatment of onychomycosis in an era of antifungal resistance: Role for antifungal stewardship and topical antifungal agents

“…Implementation of culture‐based and, in some cases, DNA‐based confirmatory testing and susceptibility testing methods may be discouraged by the days to weeks required to generate reliable results (Table 1). 86,93 Direct microscopy and lateral flow tests can rapidly detect the presence of fungal elements with good specificity for dermatophytes, but neither can identify the species, whether the pathogen is viable, or determine antifungal susceptibility 94,95 . Histopathology may be the most sensitive conventional diagnostic method, but is labour‐intensive and similarly cannot be used to identify the fungal species 95 .…”

“…Histopathology may be the most sensitive conventional diagnostic method, but is labour‐intensive and similarly cannot be used to identify the fungal species 95 . These hurdles may be overcome by the continued development of molecular‐based techniques to rapidly confirm fungal infection and fungal identity as well as detect biomarkers of antifungal resistance 93–95 . Most common and available among these are PCR‐based assays, in which fungal identification from clinical samples is enabled by amplification of species‐specific DNA, thus providing sensitivity that is similar to histopathology (e.g., periodic acid‐Schiff reaction) and greater than culture‐based or direct microscopy methods 94,96 .…”

“…Utilizing PCR in conjunction with histopathology may provide indications of the fungal species present as well as confirming its pathogenic role; this may improve diagnostic confidence, particularly in cases of onychomycosis caused by non‐dermatophyte moulds 97 . Molecular identification of fungal species can also inform treatment selection, dosing and duration 94 . For example, PCR followed by comparative sequence analysis has been used to rapidly distinguish terbinafine‐resistant from terbinafine‐susceptible strains of T .…”

“…These hurdles may be overcome by the continued development of molecular‐based techniques to rapidly confirm fungal infection and fungal identity as well as detect biomarkers of antifungal resistance 93–95 . Most common and available among these are PCR‐based assays, in which fungal identification from clinical samples is enabled by amplification of species‐specific DNA, thus providing sensitivity that is similar to histopathology (e.g., periodic acid‐Schiff reaction) and greater than culture‐based or direct microscopy methods 94,96 . Utilizing PCR in conjunction with histopathology may provide indications of the fungal species present as well as confirming its pathogenic role; this may improve diagnostic confidence, particularly in cases of onychomycosis caused by non‐dermatophyte moulds 97 .…”

“…rubrum samples were found to harbour one or more single amino acid mutations in the squalene epoxidase gene using multiplex PCR 8 . More advanced techniques (e.g., real‐time PCR and PCR‐based DNA microarray) offer additional advantages such as reduced risk of contamination, fewer false negative results and the ability to simultaneously detect multiple targets, although increased costs and equipment needs may limit their use 94 …”