Epidemiology of dermatophyte infection in Auckland, New Zealand

Epidemiology of Dermatophytes in Belgium: A 5 Years' Survey

Dermatophytes are among the most common fungal agents causing superficial skin infections worldwide. Epidemiology of these infections is evolving and variable in every country. This report presents the Belgian epidemiological data regarding the distribution of dermatophytes species isolated by the two national reference centers for mycosis during a period of 5 years (2012-2016). Trichophyton rubrum was the most frequently isolated species, considering all sampling sites (60.3% on average between 2012 and 2016). More precisely, this dermatophyte was the major agent of Tinea unguium and Tinea corporis during this period, followed by species of the Trichophyton mentagrophytes complex. Moreover, Microsporum audouinii was the main etiological agent of Tinea capitis (TC) with a frequency of 52.5% on average between 2012 and 2016. Other African dermatophytes species such as Trichophyton soudanense and Trichophyton violaceum were also agents of TC with a respective prevalence of 11.6% and 11.5% on average. This study highlights a different dermatophyte distribution in Belgium in comparison with other European countries.

Decreasing incidence of Trichophyton mentagrophytes in Korea: analysis of 6,250 cases during the last 21-year-period (1992-2012)

Trichophyton mentagrophytes is the second common dermatophyte in Korea. However, few reports have been issued on the epidemiological and mycological characteristics of T. mentagrophytes in Korea based on long-term, large-scale study. The purpose of this study was to elucidate the epidemiological and mycological characteristics of T. mentagrophytes in Korea. During the 21-yr-period from 1992 to 2012, 6,250 patients with T. mentagrophytes were surveyed to determine annual incidence and the distribution of subjects by age, sex, season, involved sites, and place of residence. T. mentagrophytes infections were confirmed by fungal culture. In addition, the colony appearance of T. mentagrophytes was classified as granular, persicolor, powdery, or downy. Epidemiological analysis showed that annual incidence reached a peak in 2005, and then gradually decreased. T. mentagrophytes infection was most common in July, and was found predominantly in middle-aged adults, especially in those in their forties. Mycological analysis showed a powdery colony appearance was the most common, followed by persicolor and granular colonies. Toewebs were most frequently involved. This investigation on T. mentagrophytes provides insights into its incidence and characteristics.

Causative agents of superficial mycoses in Istanbul, Turkey: retrospective study

The aim of the present study was to determine the percentage of agents, which can give rise to superficial fungal infections in Istanbul, Turkey. Between 2000 and 2007, the clinical samples collected from 8,200 patients attending the outpatient Dermatology Clinic at Mihrimahsultan Medical Center were examined by direct microscopy and culture. Pathogen fungi were detected in 5,722 of the patients. Of the isolates were 4,218 (74%) dermatophytes, 1,196 (21%) Candida sp., 170 (3%) Malassezia furfur, and 138 (2%) Trichosporon sp. Among the dermatophytes, Trichophyton sp. was the most common isolate followed by Epidermophyton floccosum (243) and Microsporum sp. Among the Candida species, C. albicans (549) was also frequently found. Onychomycosis was the most prevalent type of infection, followed by tinea pedis, tinea cruris, tinea corporis, and tinea capitis. In conclusion, our study showed that the most common isolated agents from superficial infections were T. rubrum being Candida sp. the second most prevalent.

Conventional methods for the diagnosis of dermatophytosis

Dermatophytes are keratinolytic fungi responsible for a large variety of diseases that can affect glabrous skin, nails and hair. In many cases, the diagnosis is not clinically obvious, and mycological analysis is required. This includes both direct microscopic examination and cultures. First of all, clinical specimens have to be sampled according to localization and characteristics of the lesions. Direct microscopic examination is usually performed using clearing reagents (KOH or Amman's chloral-lactophenol), but its sensitivity may be greatly enhanced by the use of stains or fluorochromes such as Congo red or Calcofluor white. Histological analysis is an efficient method, but it is constraining for the patients and, as direct examination, it does not allow precise identification of the pathogen. Cultures are therefore needed, and specific culture media may be used to overcome the growth of rapidly growing contaminating moulds which may hamper the recovery of dermatophytes. Identification at the species level which may be useful to initiate an appropriate treatment or for setting prophylactic measures, relies on macroscopic and microscopic morphology. Subcultures on culture media which stimulate conidiation and, for some species, the production of pigments, are often necessary. Additionally, in case of atypical isolates, some biochemical or physiological tests may be performed such as the search for urease activity or the in vitro hair perforation test. However, their contribution to species identification is rather limited, and progress is still needed for the development of biochemical or immunological tests allowing an accurate identification at the species level, pending for the availability of molecular biology-based kits.

Characteristics of superficial fungal infections in the Riyadh region of Saudi Arabia

BACKGROUND

The prevalence and characteristics of superficial fungal infections (SFIs) vary with climatic conditions, lifestyle, and population migration patterns. This study was undertaken to determine the characteristics of SFIs amongst patients visiting the dermatology clinic of Riyadh Military Hospital, Riyadh, Saudi Arabia, during the period 2003-2005.

METHODS

One hundred and nineteen patients with confirmed SFI (37 males and 82 females), aged between 5 months and 67 years, were included in this study. The diagnosis of SFI was based on clinical presentation confirmed by laboratory analysis. The type of mycotic pathogen and the site of infection were recorded as a function of age and sex.

RESULTS

Onychomycosis (40.3%) was the most frequent infection, followed by tinea capitis (21.9%), tinea pedis (16%), tinea cruris (15.1%), and tinea corporis (6.7%). Tinea capitis was most prevalent (15.1%) in children (male to female ratio, 1 : 1.57), whereas tinea pedis was most common (11.8%) in adults (male to female ratio, 1 : 2.5). Trichophyton mentagrophytes and Microsporum canis were the most common dermatophytes responsible for tinea infections, and T. mentagrophytes, Candida spp., and Aspergillus spp. were mainly responsible for onychomycosis.

CONCLUSION

The prevalence of SFI was twofold greater in females than males. Children were most commonly affected by tinea capitis, whereas adults generally suffered from tinea pedis. The frequency of onychomycosis was nearly three times higher in adults. This study clearly shows that SFIs are of concern in both genders and in all age groups.

Swimming pools and fungi: an environmental epidemiology survey in Italian indoor swimming facilities

A growing number of people attend swimming facilities for recreational activities, rehabilitative treatments, or sport. Filamentous fungi and yeast can be isolated from contaminated air, water and surfaces and may represent a biological risk for employees and users. Here we investigated the occurrence of mycotic species, in a sample of Italian swimming pools (n = 10). Detection and identification of isolated species were achieved by cultural and morphological methods. Results revealed moderate mycotic titres and a high biodiversity. Penicillium spp., Aspergillus spp., Cladosporium spp. and Alternaria sp., were constantly detected in air and surfaces sampled by the swimming area, while pathogenic yeast Candida albicans was never detected. Fusarium spp. was the most common taxon isolated from surfaces. For one facility, we typed the genotypic profiles and studied, by genetic typing, the spatial and temporal distribution of isolates. Phylogenetic relationships between species were analysed by alignment of small ribosomal subunit RNA sequences.

Five-hour diagnosis of dermatophyte nail infections with specific detection of Trichophyton rubrum

A rapid two-step DNA extraction method and a multiplex PCR for the detection of dermatophytes in general and Trichophyton rubrum specifically were developed and evaluated with DNA extracted from pure cultures and from clinically diseased nails. DNA from the following dermatophytes was used: Epidermophyton floccosum, Microsporum audouinii, Microsporum canis, Microsporum gypseum, Microsporum nanum, Trichophyton mentagrophytes, Trichophyton rubrum, Trichophyton schoenleinii, Trichophyton soudanense, Trichophyton terrestre, Trichophyton tonsurans, Trichophyton verrucosum, and Trichophyton violaceum. Human DNA and DNA from the following nondermatophyte fungi were included as controls: Alternaria, Aspergillus niger, Candida albicans, Candida glabrata, Candida krusei, Malassezia furfur, Saccharomyces cerevisiae, and Scopulariopsis brevicaulis. A total of 118 nail samples received for routine microscopy and culture for dermatophytes were subsequently tested by the two PCRs separately and in a multiplex format. Using DNA extracted from pure cultures and the pan-dermatophyte PCR, the T. rubrum-specific PCR sequentially and in a multiplex format correctly detected all dermatophytes and additionally correctly identified T. rubrum. Comparison of the traditional diagnostic evaluation (microscopy and culture) of nail samples with PCR on DNA directly extracted from the nails showed excellent agreement between PCR and microscopy, but the number of samples with dermatophyte species identification was increased considerably from 22.9% to 41.5%, mainly due to the identification of T. rubrum by PCR in microscopy-positive but culture-negative samples. In conclusion, this 5-hour diagnostic test was shown to increase not only the speed but also the sensitivity of investigation for nail dermatophytosis.

Allergy and dermatophytes

Tinea pedis (athlete's foot) and onychomycosis (infection of the toenails) caused by the dermatophyte fungus Trichophyton are highly prevalent in adults. Several Trichophyton allergens have been identified based on elicitation of immunoglobulin E antibody-mediated immediate-hypersensitivity (IH) responses. Evidence of an etiologic role for Trichophyton in asthma in some subjects with IH and chronic dermatophytosis is provided by bronchial reactivity to Trichophyton. Improvement of asthma after systemic antifungal treatment corroborates this link. A unique feature of Trichophyton allergens is the ability of the same antigen to elicit delayed-type hypersensitivity (DTH) in individuals who lack IH reactivity. Delayed responses appear to confer protection, while IH responses do not, based on the association with acute versus chronic skin infection. The amino acid sequence identity of Trichophyton allergens with diverse enzyme families supports a dual role for these proteins in fungal pathogenesis and allergic disease. Characterizing the immunologic properties of Trichophyton allergens and defining immune mechanisms which drive dichotomous responses are pivotal to understanding the dermatophyte-allergy relationship. Recent studies have identified DTH-associated major T-cell epitopes which could facilitate the development of peptide vaccines. Characterization of additional molecular targets by using new techniques may aid not only in the eradication of infection but also in the resolution of allergic symptoms.