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. In Germany, tinea capitis is mostly caused by zoophilic dermatophytes, in particular Microsporum canis. New zoophilic fungi, primarily Trichophyton species of Arthroderma benhamiae, should be taken into differential diagnostic considerations of tinea capitis, tinea faciei, and tinea corporis. Source of infection are small household pets, particularly rodents, like guinea pigs. Anthropophilic dermatophytes may be introduced by families which immigrate from Africa or Asia to Europe. The anthropophilic dermatophytes T. violaceum, T. tonsurans (infections occurring in fighting sports clubs as "tinea gladiatorum capitis et corporis") and M. audouinii are causing outbreaks of small epidemics of tinea corporis and tinea capitis in kindergartens and schools. Superficial infections of the skin and mucous membranes due to yeasts are caused by Candida species. Also common are infections due to the lipophilic yeast fungus Malassezia. Today, within the genus Malassezia more than 10 different species are known. Malassezia globosa seems to play the crucial role in pityriasis versicolor. Molds (also designated non-dermatophyte molds, NDM) are increasingly found as causative agents in onychomycosis. Besides Scopulariopsis brevicaulis, several species of Fusarium and Aspergillus are found.

Summary 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. Yeast infections affect the mucous membranes both of the gastro‐intestinal system and the genital tract as candidiasis mostly due to Candida albicans. Cutaneous candidiasis affects predominantely the intertriginous regions such as groins and the inframammary area, but also the intertriginous space of fingers and toes. In contrast, pityriasis versicolor is a superficial epidermal fungal infection primarily on the the trunk. Mold infections are rare in dermatology; they play a role nearly exclusively in nondermatophyte‐mold (NDM) onychomycosis. The diagnosis of dermatomycoses comprises the microscopic detection of fungi using the potassium hydroxide preparation or alternatively the fluorescence optical Blankophor preparation together with culture. The histological fungal detection with PAS staining possesses a high sensitivity, and it should play a more important role in particular for diagnosis of onychomycosis. Molecular biological methods, based on the amplification of fungal DNA with use of specific primers for the distinct causative agents are on the rise. With PCR, such as dermatophyte‐PCR‐ELISA, fungi can be detected directly in clinical material in a highly specific and sensitive manner without prior culture. Today, molecular methods, such as Matrix Assisted Laser Desorption/Ionization Time‐Of‐Flight Mass Spectrometry (MALDI TOF MS) as culture confirmation assay, complete the conventional mycological diagnostics.

The internal transcribed spacer (ITS) region, covering the ITS1, ITS2 and 5.8S ribosomal DNA was used to evaluate phylogenetic relationships within the fungal family Arthrodermataceae. Sequences of variable length, ranging between 522 and 684 base pairs were aligned. An unrooted consensus tree based on parsimony analysis showed Trichophyton to be polyphyletic, and Microsporum to be paraphyletic. Non-monophyly of these two genera is in conflict with traditional classification. But this relation is not strongly supported by bootstrap analysis. Phylogenetic analysis showed that the two known members of the genus Epidermophyton grouped widely apart from each other. Within Trichophyton, our results suggest a separation of human pathogenic species and primarily geophilic species. Bootstrap support for these two groups is fairly high and both groups are recognized by current taxonomy. Three lineages were revealed within the T. mentagrophytes species complex. Microsporum canis, M. audouinii and M. equinum were found to be closely related. The topology of the tree was robust to various methods of analysis (parsimony and distance) and a different weighting scheme. Weighting of transversions over transitions did not improve the status of poorly supported branches of the tree.

In the present investigation, we have shown for the first time that the onychomycosis-inducing dermatophyte Trichophyton rubrum was able to metabolize 5-aminolevulinic acid (ALA) to protoporphyrin IX (PpIX) in liquid culture medium. We have established and optimized the culture conditions and could show the typical PpIX-induced red fluorescence which was evaluated qualitatively by Wood's light examination and fluorescent microscopic analysis. The optimum concentration of ALA was in the range of 1-10 mmol l(-1). If used in higher concentrations, ALA leads to a significantly reduced growth rate and absence of PpIX formation due to highly acidic conditions. The first observation of red fluorescence was detected between 10 and 14 days poststimulation with ALA, increasing thereafter. Fluorescent microscopic examinations demonstrated that formation of PpIX was restricted to selected parts of the fungal mycelium. Repeated application of ALA in order to achieve the highest formation of PpIX in T. rubrum failed, probably due to the sustained low pH values. ALA treatment and irradiation of T. rubrum clearly demonstrated the growth-inhibiting effect of ALA PDT, either leading to reduced numbers of colonies or reduced diameters of single fungal colonies. Summarizing our results, ALA PDT might be a promising approach in the reduction of T. rubrum colonization in onychomycosis.

As expected by its global prevalence, the most frequently isolated species of yeast from vaginal swabs obtained from patients in Africa was Candida albicans, which accounted for 53 of 85 (62.4%) of the isolates from women in Madagascar and 35 of 54 (64.8%) of the culture-positive women in Angola. However, 40% of the Madagascan and 23% of the isolates from Angola, as well as two isolates obtained from one German patient, were not able to utilize the amino sugars glucosamine and N-acetylglucosamine as the sole carbon source. These isolates were able to form germ tubes but did not form chlamydospores. The correct identification as C. albicans was made possible only by using a PCR-based method of DNA fingerprinting. Only minor phenotypic and genotypic variation was observed among these strains. Whether they represent a distinct clone that is found mainly in Africa is not clear. The relevance of the amino sugar catabolic pathway in C. albicans is discussed in view of these results.

An outbreak of tinea corporis due to Trichophyton tonsurans among 46 children (aged 7-17 years) was investigated. Most of them were wrestlers. Thirty-one strains were identified by conventional methods, but proved to be problematic in 15 isolates due to colony variation and reduced sporulation. They were identified as Trichophyton tonsurans by the use of molecular methods, for example, sequence comparison of the ribosomal internal transcribed spacer (ITS) region and polymerase chain reaction fingerprinting. No DNA polymorphisms were detected with any of the techniques used, suggesting clonal reproduction of the populations of the species and providing evidence for spatial and temporal stability of the lineage.

Under the assignment of the ECMM (European Confederation of Medical Mycology) a survey regarding frequency, infectious spectrum and therapy of tinea capitis was conducted in Germany in 1998. In this survey 154 dermatology practitioners and 19 hospitals throughout Germany participated. There were 394 conditions reported, 377 with and 17 without identification of the infectious agent. The most frequent infectious agent was M. canis (n= 216; 54,8%) before T. mentagrophytes (n = 58; 14,7 %), T. verrucosum (n = 32; 8,1 %), T. violaceum (n = 24; 6, 1 %) and T. tonsurans (n = 15; 3,8%). Zoophilic dermatophytes (n = 306; 81,2%) predominated over anthropophilic species (n = 71; 18,8%) in the ratio of 4:1. Tinea capitis microsporica showed to be a more frequent infectious disease again which due to its high virulence and contagiosity of the infectious agent represents a therapeutical problem. Tinea capitis occured in an average age of 17,3 years. The preferred therapeutical regimen was a combination of systemic and topical antimycotics in 61,5% (n = 176) of the reported cases (n = 286). A solely topical or systemical monotherapy was reported in 25,2 % (n = 72) respectively 13,3 % (n = 38) of the patients. In case of systemic antimycotics the most frequent used drugs were griseofulvin (43,0%, n = 101), fluconazole (25,1%, n = 59) or itraconazole (18,7%; n = 44), in topical preparations ciclopiroxolamine dominated (53,3 %, n = 121) prior to clotrimazole (13,2%, n = 30) and terbinafine (7,1 %, n = 16). Different from the situation in Germany and in Southern Europe some of the western European countries show a tendency of an increase of anthropophilic agents in tinea capitis.

We describe a case of a 57-year-old patient with osteomyelitis at a finger of his right hand caused by Candida guilliermondii. The strains isolated were highly resistant to fluconazole and itraconazole. Using the three methods, microdilution, agardilation and E-test, the highest minimum inhibitory concentrations (MICs) amounted to > 256 micrograms ml-1 for fluconazole and > 32 micrograms ml-1 for itraconazole. To our knowledge, this is the first time such high values have been described for C. guilliermondii. They correlated with the therapeutic non-response to a triazole therapy in our patient. The patient was cured by partial amputation of the affected finger.