Expression of epidermal antimicrobial peptides is increased in tinea pedis.

BACKGROUND: Tinea pedis is often chronic or recurrent, but not all individuals are equally susceptible to this infection. Dermatophytes are able to induce the expression of antimicrobial peptides and proteins (AMPs) in human keratinocytes and certain AMPs can inhibit the growth of dermatophytes. OBJECTIVE: The focus of this study was to analyse the secretion of relevant AMPs, especially RNase 7, human beta-defensin-2 (hBD-2) and the S-100 protein psoriasin (S100A7), in patients with confirmed tinea pedis. METHODS: To verify the diagnosis, skin scales were obtained from all patients (n = 13) and the dermatophytes were identified by potassium hydroxide mount, culture and molecular analysis. To determine the AMP concentrations, the lesional skin area of the foot was rinsed with a buffer that was subsequently analysed by ELISA. The corresponding area of the other unaffected foot as well as defined healthy skin areas of the forearm and forehead and samples from age and gender-matched healthy volunteers served as controls. RESULTS: In tinea pedis patients the AMP concentrations were higher in lesional skin than in non-lesional skin and in healthy skin of controls. In particular, concentrations of hBD-2 and psoriasin were significantly elevated. CONCLUSIONS: The induction of AMPs in tinea pedis might be triggered directly by the dermatophytes; furthermore, attendant inflammation and/or differentiation processes may play a role. Our results indicate that there is no defect in the constitutive expression and induction of the analysed AMPs by dermatophytes in the epidermis of affected patients. However, it is not known why the elevated AMP concentrations fail to efficiently combat dermatophyte growth.

[Arthroderma crocatum on human skin]. / Arthroderma crocatum auf menschlicher Haut.

We report on three cases in which Arthroderma (A.) crocatum was isolated from human skin in Germany. The characteristics and epidemiology of this rare geophilic and probably mostly apathogenic dermatophyte are described paying special attention to its gymnothecia. The combination of KOH mount, culture and genetic analysis is the foundation for clinically meaningful conclusions. It is likely that the prevalence of A. crocatum is currently underestimated.

Clinical isolates of Trichophyton rubrum are completely inhibited by photochemical treatment with a γ-cyclodextrin formulation of curcuminoids.

INTRODUCTION: It was shown previously that dermatophytes can markedly be inhibited by a photochemical treatment with curcumin. This kind of photo-inactivation needs to be improved, however, because curcumin is poorly water-soluble. Therefore, a new water-soluble γ-cyclodextrin formulation of curcuminoids was tested for its photochemical inactivation of Trichophyton (T.) rubrum. MATERIALS AND METHODS: Conidia were harvested from 6 typical strains of T rubrum and used to inoculate wells of microtiter plates. These wells were also filled with a γ-cyclodextrin curcuminoid formulation with 0.1% DMSO and Sabouraud broth. The assays were then irradiated with visible light (wavelength 420 nm, 45 J/cm2 ). After 24 hours, curcuminoid was added once more, and irradiation was repeated. Fungal growth was monitored photometrically for 8 days and compared with controls. RESULTS: Growth of all 6 T rubrum strains was completely inhibited by the photochemical treatment with the γ-cyclodextrin formulation of curcuminoids. The same curcuminoid formulation applied without irradiation had only a minor inhibitory effect. DISCUSSION: Photo-inactivation of dermatophytes with a γ-cyclodextrin formulation of curcuminoids plus visible light is a very promising procedure with potential for a new treatment of patients with superficial tinea.

A human subcutaneous infection by Microascus ennothomasiorum sp. nov.

A 60-year-old woman presented with a nodular granulomatous skin lesion on her right thumb. It had developed after inoculation of a splinter of wood. Because it was resistant to various therapies, the nodule was finally excised. Complete healing followed this surgery and a melanised filamentous fungus with scopulariopsis-like morphology was recovered from the dermal tissue. Fitting with no known species, the fungus was subjected to extensive morphological, physiological and genetic investigations. It was characterised by resistance to cycloheximide, growth at 37°C, branched conidiophores with cylindrical annellides in brush-like groups producing dark conidia in basipetal chains, and cleistothecia with ellipsoidal to slightly reniform ascospores. Genetically it clustered in a well-supported clade together with Microascus (M.) brunneosporus, Microascus chinensis, Microascus intricatus, Microascus longicollis, Microascus micronesiensis and Microascus onychoides, but formed an independent branch distant from the other Microascus species. Based on its unique genetic characteristics and morphological findings, the isolate is proposed as a new species, Microascus ennothomasiorum. Morphologically it differs from its phylogenetically closest species by its branched conidiophores and ascomata with a peridium of textura intricata. Our observation once again emphasises that dermal granulomas can be caused by uncommon fungi; diagnostics should therefore include appropriate mycological investigations.

Arthroderma chiloniense sp. nov. isolated from human stratum corneum: Description of a new Arthroderma species.

A 68-year-old woman was submitted to our hospital because of erythematous and scaly skin lesions. To exclude tinea samples of stratum corneum were collected and used for mycological investigations. In this material, no fungal elements were detected microscopically, but inoculation on Sabouraud agar with cycloheximide yielded a presumptive dermatophyte fungus. Subsequent detailed investigations with conventional morphological and physiological methods and a phylogenetic analysis of the combined LSU rRNA gene (D1/D2 domains) and ITS region sequences suggested that the fungus represents a hitherto undescribed species of the genus Arthroderma. Here, we describe this species as Arthroderma chiloniense sp. nov., EMBL accession no. LT992885. This new species can be distinguished from phylogenetically related Arthroderma species using ribosomal ITS and LSU genes, and 60S L10 protein sequences; specific macroscopic, microscopic and physiological features are lacking. Our attempts to re-isolate this fungus from the patient's skin failed although her skin lesions persisted. Most likely A. chiloniense is a geophilic species that incidentally contaminated or transiently colonised the patient's skin. To avoid diagnostic misinterpretations, it is necessary to distinguish A. chiloniense from truly pathogenic dermatophytes like Trichophyton (T.) rubrum and T. interdigitale which can easily be confused with A. chiloniense based on similar mycelium morphology.

Photochemical inhibition of Trichophyton rubrum by different compoundings of curcumin.

Recently, we had shown that conidia-derived growth of many dermatophytes can be inhibited by curcumin plus exposure to visible light. This method of photo inactivation should be developed further aiming for an option to stop mycelial growth in superficial tinea. Wells of microtitre plates were inoculated with either mycelial or conidial elements collected from 5 strains of Trichophyton rubrum. Then either micellar curcumin or curcumin dissolved with DMSO was added and after 20 min the wells were filled up with Sabouraud broth. Thereafter the assays were irradiated once with visible light (wave length 420 nm, 20 J/cm2 ) and fungal growth was monitored photometrically. Identical effects were measured with conidia and mycelial elements of all 5 T. rubrum strains. Curcumin dissolved with DMSO plus irradiation had a marked dose-dependent inhibitory effect on fungal growth that was almost complete with 5.0 mg/L (P < .01) over a period of 9 days. In contrast, the same procedure with micellar curcumin had no inhibitory effect on growth obtained from conidia or mycelial elements. Mycelial elements of T. rubrum and its conidia are equally sensitive to photochemical inactivation with curcumin and the galenic compounding of curcumin is essential to achieve this photochemical effect.

Inhibition of dermatophytes by photodynamic treatment with curcumin.

Treatment of dermatophytoses with currently available antimycotic agents is often tedious and sometimes unsatisfactory. A search for better therapeutic methods-ideally with an immediate fungicidal effect-has, among others, lead to photodynamic procedures as a promising alternative, and recently curcumin was found to be a suitable agent for this application. In this study the effect of photodynamic treatment with curcumin on dermatophytes was tested in vitro. Wells of microtiter plates were filled with conidia of Trichophyton rubrum, Trichophyton interdigitale, Trichophyton terrestre, Microsporum canis, Microsporum gypseum and Epidermophyton floccosum in buffer. Then curcumin was added to the conidia and after 20 min the assays were irradiated one time only with visible light (peak wave length 367 nm, 5 J/cm2). Thereafter the wells were filled up with Sabouraud's glucose broth and in the following fungal growth was measured photometrically. The results showed that all dermatophytes were markedly inhibited depending on the concentration of curcumin. With 5.4 mg/l curcumin plus irradiation fungal growth was significantly suppressed over a period of 96 h (P < .001). Even after 96 h inhibition of T. rubrum was still complete and marked for all other species as well. M. gypseum was least susceptible. Our results are very encouraging to pursue the development of a photodynamic therapy of tinea with curcumin. The outstanding tolerance of curcumin and the innocuousness of the required light are favorable preconditions for this task.

Acyclic sesquiterpenes released by Candida albicans inhibit growth of dermatophytes.

It is unresolved as to whether fungi that share a common skin habitat might in principal interact. In in vitro screening tests with Candida albicans, Trichophytum rubrum and other common dermatophytes, we found C. albicans releases volatile compounds that inhibit growth of the dermatophytes. By applying (enantioselective) gas chromatography combined with mass spectrometry we identified 8 compounds among which stereochemically pure (3R,6E)-2,3-dihydrofarnesol (R-DHF) and (2E,6E)-farnesol (F-ol) were the main components. Synthetic R-DHF and its enantiomer, (3S,6E)-2,3-dihydrofarnesol (S-DHF), as well as F-ol were tested for their capacity to inhibit growth of dermatophytes in microtiter-plate assays over 62 h. All three compounds showed significant and concentration-dependent, to a certain extent even species-specific, inhibitory effects on T. rubrum, T. mentagrophytes, Microsporum canis and Epidermophyton floccosum. In general, S-DHF and F-ol had a pronounced effect on the dermatophytes, similar to or even stronger than that of fluconazole. E. floccosum was completely suppressed by 12.5 µg/ml dihydrofarnesol, as was the inhibition caused by 50 µg/ml fluconazole. Similarly, S-DHF- was more active against T. rubrum than fluconazole. To the best of our knowledge, 2,3-dihydrofarnesol has not yet been described as a volatile generated by microorganisms, and its inhibitory effect on dermatophytes is new to science. However, the relevance of this compound in interfungal interference in situ is unknown. In contrast, farnesol is a well-known semiochemical of C. albicans with intraspecific effects and a clear impact on other microorganisms. Mutual intermicrobial communication based on fungal volatiles therefore appears to be an exciting field for future investigations.

Inhibition of dermatophytes by the antimicrobial peptides human ß-defensin-2, ribonuclease 7 and psoriasin.

Previous studies have described some antibacterial effects of antimicrobial peptides (AMPs) expressed in human skin, but little is known about their possible activity against dermatophytes. Therefore we have tested the effects of human ß-defensin 2 (hBD-2), ribonuclease 7 (RNase 7) and psoriasin on the in vitro growth of four dermatophyte species. Germinating conidia of Trichophyton rubrum, T. mentagrophytes, Microsporum canis and Epidermophyton floccosum were exposed in vitro to hBD-2, RNase 7, psoriasin and fluconazole. Subsequent fungal growth was measured photometrically over 168 hours. All AMPs significantly inhibited fungal growth, with the degree of inhibition dependent on the dermatophyte species and the specific AMP. E. floccosum was found to be the most susceptible species in that it was markedly suppressed by all AMPs, whereas M. canis was inhibited only by psoriasin. Overall, psoriasin was the most effective AMP and had even stronger inhibitory effects on some dermatophytes than fluconazole. Our findings show that AMPs expressed in human skin can, in principal, inhibit the growth of dermatophytes in vitro. Therefore the question whether AMPs are relevant for human protection against tineas is justified and should be addressed by investigating their role in vivo.

Tinea capitis and tinea corporis with a severe inflammatory response due to Trichophyton tonsurans.

Trichophyton tonsurans is an anthropophilic dermatophyte, with a worldwide distribution, although its prevalence varies considerably between different geographical regions. Whereas in North America infections due to this fungus are exceptionally common, on the European continent they appear relatively seldom. Although T. tonsurans is primarily associated with tinea capitis, it can also be the cause of tinea corporis and tinea unguium. The course of infection is usually only mildly symptomatic. We describe here two cases of urease-positive T. tonsurans infections with atypically extensive cutaneous lesions and severe inflammatory responses. .