Detection and identification of dermatophytes based on currently available methods – a comparative study

Abstract

Aims: Accurate identification of dermatophytes is essential for implementing appropriate antifungal treatment and epidemiological analysis. However, the limitations of conventional diagnostics are a frequently discussed topic, and new diagnostic techniques are constantly expanding. In this study, we assess the suitability of conventional diagnostic techniques in comparison to the realtime PCR assay and MALDI-TOF MS in detection and identification of dermatophytes. Methods and Results: Strains included in this study were obtained from human and animals with symptomatic, and asymptomatic infection. A direct examination revealed that 31Á7 and 60Á9% of samples from symptomatic patients, and 25Á7 and 60% from asymptomatic animals were positive, as shown by light and fluorescence microscopy respectively. In turn, dermatophytes were isolated from 90Á2 and 71Á4% of these samples. The pandermatophyte primers in real-time PCR assay facilitated detection in 85Á3 and 82Á9% of the symptomatic and asymptomatic dermatophytoses respectively. Additionally, species-specific PCR assays were positive in 70Á7 and 37Á1% of these samples. The MALDI-TOF MS analysis yielded positive results consistent with conventional techniques in 97Á2 and 72% of symptomatic and asymptomatic infections respectively. Conclusions: Our study revealed that there is no universal diagnostic method that would be ideal in each of the cases considered. Nonetheless, conventional techniques are still the most effective and reliable tools for mycological diagnostics. Significance and Impact of the Study: Dermatologists and veterinarians have difficulties in making a diagnosis of dermatophytoses based only on observed symptoms of fungal infections, as they mimic symptoms of other dermatoses. In this context, a comparative analysis of the results of diagnostics performed using conventional methods and new technologies are crucial for implementing these pioneer methods into routine laboratory practice.

Real-Time PCR as an Alternative Technique for Detection of Dermatophytes in Cattle Herds

“…Moreover, the agreement of the positive qPCR result with the dermatophyte culture was 10.98% (50% vs. 39.02%) higher for this method than for the microscopic examination. Gnat et al [23] revealed that the qPCR method with pan-dermatophyte primers detected dermatophytes in a sample with a 24.5% (85.4% vs. 60.9%) and 53.7% (85.4% vs. 31.7%) higher efficiency than direct analysis in fluorescence and light microscopy, respectively. This result was therefore much better than that obtained in the present research, the reasons for which can be found in the greater diversity of the analyzed samples.…”

“…Mycological procedures, i.e., detection and species identification of the isolates, were performed with a few modifications, as described previously by Gnat et al [23]. For the qPCR technique (P), DNA was extracted using a DNeasy Blood & Tissue Kit (Qiagen, Hilden, Germany), according to the manufacturer's instructions.…”

“…This issue is especially important in cowsheds where vaccinated and unvaccinated animals are kept. The application of conventional methods of detection and identification of dermatophytes in cattle herds has several drawbacks, as they are laborious and time-consuming and necessitate the experience of a mycological diagnostician [22][23][24]. Technologically advanced methods of dermatophyte identification developed recently include molecular methods based on PCR [25,26].…”

Expression of epidermal antimicrobial peptides is increased in tinea pedis

“…Although some patients had macroscopically conspicuous lesions, no dermatophyte was detected by extensive mycological diagnostics. Detection of fungi involved in superficial skin infections by conventional methods still is the gold standard though it is very time‐consuming and not always successful 20 . The limitations of conventional diagnostics are therefore a frequently discussed topic, as new diagnostic techniques are constantly expanding.…”

Human Mycobiome In Normobiosis And Dysbiosis States Characteristics And Analysis Methods

“…W niektórych przypadkach dokładna identyfikacja na poziomie gatunku nie jest możliwa wyłącznie w oparciu o sekwencjonowanie regionów ITS [38,39,46]. Obecnie jednak nie są znane alternatywne markery molekularne, dla których uzyskuje się porównywalną zdolność rozdzielczą.…”