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The spectrum of dermatophytes isolated from skin lesions had changed in last 70 years. Before the Second World War in Germany, Microsporum audouinii and Epidermophyton floccosum ranked the first, whereas Trichophyton rubrum is the most common dermatophyte since the fifties of last century, accounting for 80-90% of the strains, followed by T. mentagrophytes. This evolution is typical for Central and North Europe and it needs to be connected with the increase in the incidence of tinea pedis. In contrast, in Southern Europe and in Arabic countries, zoophilic dermatophytes, such as Microsporum canis or Trichophyton verrucosum, are the most frequently isolated. In Europe, especially in Mediterranean countries, the incidence of M. canis infection has strongly increased during the recent years and this dermatophyte is now the most prevalent in tinea capitis in children. An analysis of the frequency and distribution of tinea pedis in different occupations and leisure-time activities as well as the routes of infection are reported. The spreading of this disease in most developed countries of the world represents a considerable economic problem, since it was accompanied by a parallel increase in the frequency of onychomycosis which implies, as tinea pedis, large financial charges. In poor developing countries, mycoses appear endemically, primarily with children, and their treatment often fails because of the lack of efficient antifungals. The particular epidemiological situations of dermatophytoses and the pathogenic spectrum of dermatophytes are examined at the example of numerous countries.

Under steady-state conditions, the immune system is poised to sense and respond to the microbiota. As such, immunity to the microbiota, including T cell responses, is expected to precede any inflammatory trigger. How this pool of preformed microbiotaspecific T cells contributes to tissue pathologies remains unclear. Here, using an experimental model of psoriasis, we show that recall responses to commensal skin fungi can significantly aggravate tissue inflammation. Enhanced pathology caused by fungi preexposure depends on Th17 responses and neutrophil extracellular traps and recapitulates features of the transcriptional landscape of human lesional psoriatic skin. Together, our results propose that recall responses directed to skin fungi can directly promote skin inflammation and that exploration of tissue inflammation should be assessed in the context of recall responses to the microbiota.

Dermatophytes represent the largest and most common group of fungal infections, impacting 25% of the global population. Among them, Trichophyton rubrum has emerged as the predominant species, responsible for a range of conditions such as tinea corporis, tinea pedis, onychomycosis, tinea cruris, and tinea manuum. Although dermatophyte incidence varies geographically, there is a noticeable rise in cases caused by T. indotineae, a strain that exhibits resistance to terbinafine. In the past decade zoophilic dermatophyte T. mentagophytes genotype VII (now known as T. interdigitale) gains a growing importance, due to its increasing frequency, the severity of the clinical manifestation and mode of transmission. Tinea infections present with various clinical symptoms and can affect individuals of all ages, from tinea pedis in adults to tinea capitis in children. Among adults globally, tinea unguium (onychomycosis) is the most common form of dermatophytosis, affecting 5.5% of the general population. Tinea unguium is more frequently seen in developed countries, while tinea capitis is more common in developing nations. The COVID-19 pandemic has led to an increase in cases of tinea faciei, likely due to prolonged mask-wearing. Terbinafine remains the preferred treatment for dermatophyte infections worldwide due to its potent fungicidal properties, minimal risk of drug interactions, and fewer side effects compared to other oral antifungals. Itraconazole and terbinafine appear to be equally effective and safe for treating tinea cruris and tinea corporis. However, the rising resistance of dermatophytes to these antifungal drugs, along with frequent recurrences of dermatophytosis in certain regions, is becoming a significant public health concern.

Identification of fungi in dermatological samples using PCR is reliable and provides significantly improved results in comparison with cultures. It is possible to identify the infectious agent when negative results are obtained from cultures. In addition, identification of the infectious agent can be obtained in 1 day. Conventional and real-time PCR methods used for direct fungus identification in collected samples vary by DNA extraction methods, targeted DNA and primers, and the way of analysing the PCR products. The choice of a unique method in a laboratory is complicated because the results expected from skin and hair sample analysis are different from those expected in cases of onychomycosis. In skin and hair samples, one dermatophyte among about a dozen possible species has to be identified. In onychomycosis, the infectious agents are mainly Trichophyton rubrum and, to a lesser extent, Trichophyton interdigitale , but also moulds insensitive to oral treatments used for dermatophytes, which renders fungal identification mandatory. The benefits obtained with the use of PCR methods for routine analysis of dermatological samples have to be put in balance with the relative importance of getting a result in a short time, the price of molecular biology reagents and equipment, and especially the time spent conducting laboratory manipulations.

The dermatophytes are among the most frequently observed organisms in biomedicine, yet there has never been stability in the taxonomy, identification and naming of the approximately 25 pathogenic species involved. Since the identification of these species is often epidemiologically and ethically important, the difficulties in dermatophyte identification are a fruitful topic for modern molecular biological investigation, done in tandem with renewed investigation of phenotypic characters. Molecular phylogenetic analyses such as multilocus sequence typing have had to be tailored to accommodate differing the mechanisms of speciation that have produced the dermatophytes that are commonly seen today. Even so, some biotypes that were unambiguously considered species in the past, based on profound differences in morphology and pattern of infection, appear consistently not to be distinct species in modern molecular analyses. Most notable among these are the cosmopolitan bane of nails and feet, Trichophyton rubrum , and the endemic African agent of childhood tinea capitis, Trichophyton soudanense , which are effectively inseparable in all analyses. The molecular data require some reinterpretation of results seen in conventional phenotypic tests, but in most cases, phylogenetic insight is readily integrated with current laboratory testing procedures.

Dermatophytosis is among the most common superficial mycoses in Iran. The purpose of this report was to update the clinical and mycological features of human dermatophytosis in the Khuzestan, southwestern Iran. In the framework of a one-year survey, a total of 4120 skin, hair and nail samples obtained from the outpatients with symptoms suggestive of tinea were analyzed by using direct microscopy, culture and molecular identification methods. Strains isolated from cultures were subjected to amplification of the nuclear rDNA ITS regions in a PCR assay followed by an early established RFLP analysis. For confirmation of species identification, 100 isolates as representatives of all presumable species were subjected to ITS sequencing. Infection was confirmed in 1123 individuals (27.25 %) in the age range of 1–89 years by direct microscopy and/or culture including 603 males versus 520 females. Frequencies of infections were the highest and the lowest in age groups of 21–30 and 11–20 years, respectively. Tinea corporis was the most prevalent clinical manifestation followed by tinea cruris, tinea capitis, tinea manuum, tinea pedis, tinea unguium, tinea faciei and tinea barbae. Trichophyton interdigitale (58.7 %) was the most dominant isolate followed by Epidermophyton floccosum (35.4 %), Microsporum canis (3 %), T. rubrum (1.5 %), T. species of Arthroderma benhamiae (0.5 %), T. tonsurans (0.3 %) and T. violaceum (0.3 %). Other species included M. gypseum , M. fulvum and T. verrucosum (each one 0.1 %). Such a high occurrence of infection with T. interdigitale , which has not been reported from Iran, is due to the use of accurate molecular methods based on new species concept in dermatophytes. The prevalence of dermatophytoses caused by zoophilic species remarkably increased and Trichophyton species of A. benhamiae has emerged as a new agent of dermatophytosis in southwestern Iran, while infections due to anthropophilic species, except E. floccosum, took a decreasing trend.

MALDI-TOF MS has become increasingly popular for microorganism identification in the routine laboratory. Compared with conventional morphology-based techniques, MALDI-TOF is relatively inexpensive (per-unit identification), involves a rapid result turnaround time and yields more accurate results without the need for highly qualified staff. However, this technology has been technically difficult to implement for filamentous fungi identification. Identification of dermatophytes, a type of filamentous fungi, remains particularly challenging, partly due to the lack of clear species definition for some taxa or within some species complexes. Review of the ten studies published between 2008 and 2015 shows that the accuracy of MALDI-TOF MS-based identification varied between 13.5 and 100 % for dermatophytes. This variability was partly due to inconsistencies concerning critical steps of the routine clinical laboratory process. Use of both a complete formic acid-acetonitrile protein extraction step and a manufacturer library supplemented with homemade reference spectra is essential for an accurate species identification. This technique is conversely unaffected by variations in other routine clinical laboratory conditions such as culture medium type, incubation time and type of mass spectrometry instrument. Provided that a reference spectra library is adequate for dermatophyte identification, MALDI-TOF MS identification is more economical and offers an accuracy comparable to that of DNA sequencing. The technique also represents an advantageous alternative to the protracted and labor-intensive dermatophyte identification via macroscopic and microscopic morphology in the routine clinical laboratory.

Background High-throughput sequencing has led to increased insights into the human skin microbiome. Currently, the majority of skin microbiome investigations are limited to characterizing prokaryotic communities, and our understanding of the skin fungal community (mycobiome) is limited, more so for cohorts outside of the western hemisphere. Here, the skin mycobiome across healthy Chinese individuals in Hong Kong are characterized. Results Based on a curated fungal reference database designed for skin mycobiome analyses, previously documented common skin colonizers are also abundant and prevalent in this cohort. However, genera associated with local terrains, food, and medicine are also detected. Fungal community composition shows interpersonal (Bray-Curtis ANOSIM = 0.398) and household (Bray-Curtis ANOSIM = 0.134) clustering. Roles of gender and age on diversity analyses are test- and site-specific, and, contrary to bacteria, the effect of household on fungal community composition dissimilarity between samples is insignificant. Site-specific, cross-domain positive and negative correlations at both community and operational taxonomic unit levels may uncover potential relationships between fungi and bacteria on skin. Conclusions The studied Chinese population presents similar major fungal skin colonizers that are also common in western populations, but local outdoor environments and lifestyles may also contribute to mycobiomes of specific cohorts. Cohabitation plays an insignificant role in shaping mycobiome differences between individuals in this cohort. Increased understanding of fungal communities of non-western cohorts will contribute to understanding the size of the global skin pan-mycobiome, which will ultimately help understand relationships between environmental exposures, microbial populations, and the health of global humans.

BackgroundWith the rapid development of the economy and changes in lifestyle in recent years, the epidemiological pattern of dermatophytosis has changed. We analyzed the epidemiological features of dermatophytosis in a hospital in Hangzhou from 2018 to 2023.MethodsData from patients with culture-positive dermatophytosis were obtained from the Laboratory Information System of the Mycology Laboratory of our hospital. Dermatophyte isolates were mainly identified by macroscopic and microscopic features of the colonies.ResultsThere were 32,786 patients with culture-positive dermatophytosis during the 6-year period, including 16,789 male patients and 15,990 female patients. Patients’ ages ranged from 1 month to 97 years. Tinea unguium accounted for the largest proportion (14,879, 45.38%), which was mainly prevalent among females (8946, 60.13%). Significant gender differences were observed in all clinical types of dermatophytosis, except for tinea pedis. In total, 15,486 (47.73%) patients aged 21–40 years. The median age of patients with tinea manum and tinea capitis was the highest (49 years) and the lowest (5 years), respectively. Nine species of isolated dermatophytes were identified, of which Trichophyton rubrum accounted for 90.20% (29,573 cases). M. canis accounted for 66.80% of isolated dermatophytes from tinea capitis. The isolation rates of zoophilic species were 43.41% in tinea faciei and 18.90% in tinea corporis.ConclusionT. rubrum was absolutely predominant agent of dermatophytosis except tinea capitis in which M. canis was the most common organism. The prevalence of zoophilic dermatophytes has increased in tinea faciei and tinea corporis. Tinea unguium was the major clinical form of dermatophytosis, and it was more prevalent among females. The onset peak of dermatophytosis was in the age group of 21–40 years, except for tinea capitis.