P. Nenoff

Antifungal activity of the essential oil of Melaleuca alternifolia (tea tree oil) against pathogenic fungi in vitro.

The in vitro antifungal activity of tea oil, the essential oil of Melaleuca alternifolia, has been evaluated against 26 strains of various dermatophyte species, 54 yeasts, among them 32 strains of Candida albicans and other Candida sp. as well as 22 different Malassezia furfur strains. Minimum inhibitory concentrations (MIC) of tea tree oil were measured by agar dilution technique. Tea tree oil was found to be able to inhibit growth of all clinical fungal isolates. For the investigated dermatophytes MIC values from 1,112.5 to 4,450.0 micrograms/ml with a geometric mean of 1,431.5 micrograms/ml were demonstrated. Both C. albicans strains and the other strains belonging to the genus Candida and Trichosporon appeared to be slightly less susceptible to tea tree oil in vitro. However, their MIC values, which varied from 2,225.0 to 4,450.0 micrograms/ml (geometric mean 4,080 micrograms/ml), indicated moderate susceptibility to the essential oil of M. alternifolia. The lipophilic yeast M. furfur seemed to be most susceptible to tea tree oil. MIC values between 556.2 and 4,450.0 micrograms/ml (geometric mean 1,261.5 micrograms/ml) were found against the tested M. furfur strains. However, when calculated as percentage tea tree oil of the agar, the above-mentioned concentrations correspond to 0.5-0.44% tea tree oil content. These values are far below the usual relatively high therapeutic concentrations of the agent; approximately 5-10% solution or even the concentrated essential oil are used for external treatment. In comparison with tea tree oil, in vitro susceptibility against miconazole, an established topical antifungal, was tested. As expected, very low MIC values for miconazole were found for dermatophytes (geometric mean 0.2 microgram/ml), yeasts (geometric mean 1.0 microgram/ml), and M. furfur (geometric mean 2.34 micrograms/ml). It is suggested that the in vivo effect of tea tree oil ointment in the therapy of fungal infections of the skin and mucous membranes as well as in the treatment of dandruff, a mild form of seborrheic dermatitis, may be at least partly due to an antifungal activity of tea tree oil.

Mycology – an update. Part 1: Dermatomycoses: Causative agents, epidemiology and pathogenesis

Dermatomycoses are caused most commonly by dermatophytes. The anthropophilic dermatophyte Trichophyton rubrum is still the most frequent causative agent worldwide. Keratinolytic enzymes, e.g. hydrolases and keratinases, are important virulence factors of T. rubrum. Recently, the cysteine dioxygenase was found as new virulence factor. Predisposing host factors play a similarly important role for the development of dermatophytosis of the skin and nails. Chronic venous insufficiency, diabetes mellitus, disorders of cellular immunity, and genetic predisposition should be considered as risk factors for onychomycosis. A new alarming trend is the increasing number of cases of onychomycosis – mostly due to T. rubrum – in infancy.

Trichophyton mentagrophytes sive interdigitale? A dermatophyte in the course of time

Originally, the Trichophyton (T.) mentagrophytes complex distinguished between the anthropophilic subspecies T. mentagrophytes var. interdigitale, T. mentagrophytes var. nodulare (synonym T. krajdenii), and T. mentagrophytes var. goetzii and the zoophilic subspecies T. mentagrophytes var. granulosum (rodents), T. mentagrophytes var. erinacei (hedgehog), and T. mentagrophytes var. quinckeanum (mice). In addition, two sexual species (teleomorph) of this complex are known. These are Arthroderma (A.) benhamiae Ajello and Cheng 1967 and Arthroderma vanbreuseghemii Takashio 1973.

[Causative agents of onychomycosis--a retrospective study].

Background: Dermatophytes, yeasts and moulds all are potential causative agents of onychomycosis.The aim of this study was to determine the percentage of cases of onychomycoses caused by each group. In addition, the responsible genus and species was identified for each nail infection.

Mycology – an update Part 2: Dermatomycoses: Clinical picture and diagnostics

Most fungal infections of the skin are caused by dermatophytes, both in Germany and globally. Tinea pedis is the most frequent fungal infection in Western industrial countries. Tinea pedis frequently leads to tinea unguium, while in the elderly, both may then spread causing tinea corporis. A variety of body sites may be affected, including tinea glutealis, tinea faciei and tinea capitis. The latter rarely occurs in adults, but is the most frequent fungal infection in childhood. Following antifungal treatment of tinea unguium and also tinea capitis a dermatophytid or hyperergic reaction to dermatophyte antigens may occur.

Sarcoidosis of the skin--a dermatological puzzle: important differential diagnostic aspects and guidelines for clinical and histopathological recognition.

Sarcoidosis of the skin may have an extremely heterogeneous clinical presentation, so that the definitions of ‘great imitator’ and ‘clinical chameleon’ have long been used. There is, in fact, a large group of skin diseases that can enter the differential diagnosis with cutaneous sarcoid manifestations, either clinically or/and pathologically. As the clinical consequences and the prognosis of these groups of diseases are often very different, it is important to correctly plan the diagnostic workup. The diagnostic process in this case often presents a challenge as no single test is sufficiently specific, so that a certain diagnosis can be only made in the presence of a compatible clinical and radiographic picture, along with histopathological evidence of non‐necrotizing, epithelioid cell granulomas, and exclusion of other potential aetiologies. For practical reasons, four main groups of skin conditions capable of mimicking sarcoidosis can be identified: (i) transmissible, infectious diseases; (ii) allergic and immunological manifestations of various aetiologies; (iii) granulomatous diseases of various aetiologies; and (iv) lymphomas and pseudolymphomas. The aim of this article is to describe the main clinical and histopathological findings of such disease entities, and to discuss the role of those features (morphological, pathological and laboratory) that can help distinguish them from sarcoidosis of the skin.

Trichophyton species of Arthroderma benhamiae - a new infectious agent in dermatology

In Germany, infections due to the zoophilic dermatophyte Trichophyton (T.) species of Arthroderma benhamiae are being more frequently diagnosed. The source of infection of this emerging pathogen overlaps with that of the zoophilic species T. interdigitale. The most common source are guinea pigs. T. species of Arthroderma benhamiae causes inflammatory dermatophytosis in children and adolescents. In addition to tinea capitis, it may cause both tinea corporis, tinea manus and frequently tinea faciei. In Germany, T. species of Arthroderma benhamiae is a frequent zoophilic dermatophyte, which in regions is probably more frequent than Microsporum canis. The mycological identification of the isolates with their yellow stained colonies is based on their macroscopic and microscopic features. However, some exhibit colony features consistent with those of T. interdigitale. These strains only can be identified unambiguously by means of molecular techniques. Using detection methods such as PCR‐ELISA or real‐time PCR, the dermatophyte can be identified directly from clinical material. Sequencing of the internal transcribed spacer region (ITS) of the ribosomal DNA has been approved as culture confirmation test for T. species of Arthroderma benhamiae. In addition, matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry (MALDI TOF MS) is useful. Widespread dermatophytosis due to T. species of Arthroderma benhamiae, in particular of tinea capitis, requires oral antifungal agents. Terbinafine is most effective, alternatives are fluconazole and itraconazole.

Molekularbiologischer Direktnachweis von Dermatophyten im klinischen Material bei Verdacht auf Onychomykose und Tinea pedis

BACKGROUND The prevalence of onychomycosis is rising worldwide. Before starting antifungal treatment, an exact mycological diagnosis should be obtained. The current laboratory diagnosis of dermatomycoses is based on the detection of the causative agent by microscopy and culture. These conventional diagnostic methods for fungal infections often are not the best solution because they are time-consuming, cultures are false-negative and direct examination identifies non-vital structures which cannot be used for speciation. PATIENTS AND METHODS A total of 218 patients presenting in a surgical practice over 3 months with clinical signs of tinea pedis and/or onychomycosis were involved in the prospective study. All patients had predisposing factors for tinea pedis and tinea unguium, such as vascular insufficiency, diabetes mellitus, and leg ulcers. Nail specimens and skin scrapings were investigated for fungi using Blancophor® preparation, and cultured. In addition to conventional diagnostics, PCR (polymerase chain reaction) for detection of dermatophyte DNA was employed. This PCR-Elisa assay is based on the use of specific primers which target the topoisomerase II gene. This allows the highly specific molecular identification of Trichophyton (T.) rubrum, T. interdigitale, and Epidermophyton floccosum directly in clinical samples. RESULTS 23.9 % of patients were culture-positive for dermatophytes (either T. rubrum, or T. interdigitale). With PCR, dermatophyte DNA either of T. rubrum or T. interdigitale could be detected in nail samples and skin scrapings from at least 29.9 % of all patients. Epidermophyton floccosum was not found in this study, neither by cultivation nor by PCR. The diagnostic sensitivity of the PCR-Elisa assay was calculated as 79.0% ; the diagnostic specificity as 85.5 %. CONCLUSION PCR-Elisa evaluation makes possible a rapid, specific and sensitive diagnosis of dermatophytosis of the nails and skin within 24 (maximal 48) hours with identification of the involved species.

Mycology – an update Part 3: Dermatomycoses: topical and systemic therapy

Treatment of dermatophyte infections is based on the clinical picture and mycological detection of the causative pathogen. Based on the appropriate indication, onychomycosis can be treated topically using an antimycotic nail lacquer. Atraumatic nail abrasion with 40 % urea ointment has a beneficial effect on healing. Continuous treatment of onychomycosis with terbinafine represents the most effective systemic therapy. Terbinafine or itraconazole are the safest and most effective antimycotic agents for the treatment of onychomycosis in children. For laser therapy of onychomycosis, only a few studies on clinical efficacy are available. Regarding tinea capitis, targeted species‐specific therapy of dermatophytosis of the scalp is currently recommended. Terbinafine, yet also itraconazole and fluconazole, are effective in tinea capitis caused by Trichophyton species. Microsporum infections of the scalp are preferably treated with griseofulvin, alternatively with itraconazole or fluconazole. Terbinafine is less effective.

Antifungal efficacy of lasers against dermatophytes and yeasts in vitro.

Abstract Purpose: Approximately 2–13% of the world population suffers from onychomycosis. Recently, lasers have been introduced for treatment. However, no effect was found with in vitro laser irradiation of pathogens on agar plates. This study aimed to investigate the efficacy of laser irradiation against fungi using an alternative in vitro approach. Materials and methods: Lasers of 808, 980 and 1064 nm were used to heat cell culture media and a nail clipping. Trichophyton rubrum. T. interdigitale. Microsporum gypseum. Candida albicans. C. parapsilosis, and C. guilliermondii species were subcultured and subjected to laser treatments (808/980 nm: 9–27 J/cm2, 6 ms, 12 × 12 or 12 × 50 mm and 1064 nm: 50–240 J/cm2, 90 ms, 5–10 mm). After irradiation, the fungal elements were transferred onto agar plates using conventional and Drigalski spatulas and were incubated for 6 days. Results: The highest increase in temperature was found using a 980-nm laser with a pulse duration of 6 ms and a fluence of 27 J/cm2. The histology work-up revealed a dissection of the nail plate from the nail bed tissue after laser irradiation. Growth inhibition was only found for C. guilliermondii and T. interdigitale. All other pathogens presented only reduced growth, and C. albicans growth was unaffected. Conclusions: This study demonstrates a clear thermal effect for linear scanning 980-nm and long-pulsed 1064-nm laser systems on either nail clippings or cell culture media. Complete pathogen growth impairment was achieved if temperatures were measured above 50 °C. The results for the 1064-nm system were almost comparable to 980 nm results.