Updates on the Epidemiology of Dermatophyte Infections

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.     

Tinea Unguium: Diagnosis and Treatment in Practice

Onychomycosis is caused by dermatophytes, yeasts or non-dermatophyte molds; when caused by dermatophytes, it is called tinea unguium. The main etiological agents are Trichophyton rubrum and Trichophyton interdigitale. The most frequent types are distal and lateral subungual onychomycosis. Diagnosis usually requires mycological laboratory confirmation. Dermoscopy can be helpful and also biopsy is an excellent diagnostic method in uncommon cases or when mycological test is negative. Treatment must be chosen according to clinical type, number of affected nails and severity. The goal for antifungal therapy is the clearing of clinical signs or mycological cure.     

甲癣局部用药体外药效实验方法研究进展

甲真菌病是皮肤科的常见病,是由皮肤癣菌、酵母菌和非皮肤癣菌性霉菌侵犯甲板和(或)甲床所致的病变,其中由皮肤癣菌感染引起的甲真菌病称为甲癣。人甲板中角蛋白硬、厚且致密,从而形成一个完美屏障。针对甲板的特殊解剖结构,需要局部治疗药物具备穿透指甲屏障,体现高活性抗皮肤癣菌的特质。目前,甲癣的局部用药体外药效学研究没有统一的标准,缺乏指导依据。本文查阅近年来文献报道,综述甲癣局部治疗药物的体外药敏实验、药物与甲板内角蛋白亲和力实验以及药物在甲板内的渗透等,并阐述上述实验方法的模型选择、方式方法及方法间的比较,以推荐适合化合物筛选的方法。     

Pathogenic Dermatophytes Survive in Nail Lesions During Oral Terbinafine Treatment for Tinea Unguium

Tinea unguium caused by dermatophyte species are usually treated with oral antimycotic, terbinafine (TBF). To understand the mechanisms of improvement and recalcitrance of tinea unguium by oral TBF treatment, a method of quantifying dermatophyte viability in the nail was developed, and the viability of dermatophytes was analyzed in toenail lesions of 14 patients with KOH-positive tinea unguium treated with oral TBF 125 mg/day for up to 16 weeks. Mycological tests, including KOH examination and fungal culture, and targeted quantitative real-time PCR for internal transcribed spacer (ITS) region, including rRNA, were demonstrated at the initial visit and after 8 and 16 weeks of treatment. Assays in eight patients showed that average ITS DNA amount significantly decreased, to 44% at 8 weeks and 36% at 16 weeks compared with 100% at initial visit. No significant difference was observed between at 8 and 16 weeks, despite the TBF concentration in the nail supposedly more than 10-fold higher than the minimum fungicidal concentration for dermatophytes. This finding suggests the pathogenic dermatophytes in nail lesions could survive in a dormant form, such as arthroconidia, during oral TBF treatment. Both antimycotic activity and nail growth are important factors in treatment of tinea unguium.     

Mycological study of 100 cases of ungual lesions of Rosario city (Republica Argentina)

The aim of present work was to analyze several diagnostic methods of nail infections relating to various etiological agents with the different types of lesions and their probable predisposing causes. One hundred nail samples were studied including the following laboratory test: Direct microscopic exams with 40% KOH, direct exams in fluorescence microscope with calcoflúor white and mycological cultures. One or more of these methods gave positive results in 65% of the samples tested. The fungi isolated by culture were the following: Candida (predominantly non-albicans, which appeared in 70.8% of the cases), dermatophytes (25% of the cases) and opportunistic fungi (4.2%). Females showed a higher incidence of fungal infection. Candida were more frequent in finger nails, while dermatophytes occurred mainly in toe nails. The clinical characteristic of the lesions produced by Candida were: tricophytoid type (67%) and periungeal type (33%). On the other hand, dermatophytes and opportunistic fungi produced distal subungual type lesions. Since correlation between direct examination and cultures is not always found in mycological studies, based in our present results we suggest that, although they must always be carried out, both should be repeated with the addition of direct examination with calcoflúor in the cases in which the diagnosis is difficult.     

The New Species Concept in Dermatophytes—a Polyphasic Approach

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.     

面癣118例的真菌学和临床因素分析

目的探讨面癣的致病菌、临床特点、易感年龄等相关因素。方法分析本院门诊2012年1～6月的真菌直接涂片镜检发现菌丝或孢子的面癣患者。记录患者的一般资料、有无动物接触史、有无并发其他部位浅部真菌病、用药史。取皮屑直接镜检的同时进行真菌培养鉴定。结果面癣见于各年龄段,在51～70岁之间有一个年龄高峰。分离皮肤癣菌103株,包括红色毛癣菌70株(68.0%)、犬小孢子菌21株(20.4%)、须癣毛癣菌10株(9.7%)、石膏样小孢子菌2株(1.9%)。合并其他浅部真菌病、使用激素类药物、动物接触史是面癣发病的重要因素。部分炎症明显的面癣使用医用拭子取材,可以提高真菌涂片和培养的质量。结论不典型的面癣容易误诊,需要高质量的真菌镜检和培养,降低面癣误诊率。     

Dermatology for the practicing allergist: Tinea pedis and its complications

Tinea pedis is a chronic fungal infection of the feet, very often observed in patients who are immuno-suppressed or have diabetes mellitus. The practicing allergist may be called upon to treat this disease for various reasons. Sometimes tinea infection may be mistaken for atopic dermatitis or allergic eczema. In other patients, tinea pedis may complicate allergy and asthma and may contribute to refractory atopic disease. Patients with recurrent cellulitis may be referred to the allergist/immunologist for an immune evaluation and discovered to have tinea pedis as a predisposing factor. From a molecular standpoint, superficial fungal infections may induce a type2 T helper cell response (Th2) that can aggravate atopy. Th2 cytokines may induce eosinophil recruitment and immunoglobulin E (IgE) class switching by B cells, thereby leading to exacerbation of atopic conditions. Three groups of fungal pathogens, referred to as dermatophytes, have been shown to cause tinea pedis: Trychophyton sp, Epidermophyton sp, and Microsporum sp. The disease manifests as a pruritic, erythematous, scaly eruption on the foot and depending on its location, three variants have been described: interdigital type, moccasin type, and vesiculobullous type. Tinea pedis may be associated with recurrent cellulitis, as the fungal pathogens provide a portal for bacterial invasion of subcutaneous tissues. In some cases of refractory asthma, treatment of the associated tinea pedis infection may induce remission in airway disease. Very often, protracted topical and/or oral antifungal agents are required to treat this often frustrating and morbid disease. An evaluation for underlying immuno-suppression or diabetes may be indicated in patients with refractory disease.     

Griseofulvin in the treatment of dermatomycoses and onychomycoses produced by dermatophytes of the Trichophyton group

Summary Based on observations on the therapy of 128 patients affected with tinea unguium, tinea manus et pedis, tinea granulomatosa nodularis (Granuloma Majocchi), tinea cruris, tinea corporis, tinea barbae and tinea capitis due to infection with dermatophytes of theTrichophyton group, determinations were made for the absolute and relative indication of griseofulvin in the treatment of these mycoses. For each affection, comparisons were made between the therapeutic results obtained by combined therapy with oral griseofulvin (uniform daily dose 1 g for each case) and local therapy with 1 % water solution organic dyes, coal tar on the one hand, and mere local therapy as described above, on the other. For treatment, griseofulvin of different production was available: British Grisovin, Likuden and Likuden M from West-Germany, and Griseofulvin produced in the German Democratic Republic. No essential differences were found in the therapeutic effect of the individual preparations, the tolerance, however, was found to be best with Likuden. On the basis of comparisons made for the results of the individual methods of treatment, griseofulvin therapy was found to be an absolute indication of the mycotic diseases as follows: tinea capitis, tinea cruris follicularis trichophytica and tinea unguium. A relative indication was found to be tinea corporis, tinea barbae, tinea cruris, and tinea manus et pedis.All patients were subjected to microscopic and culture examination. The frequency of the individual dermatophytes was as follows:Trichophyton rubrum in 56 cases,Trichophyton verrucosum in 19 cases,Trichophyton mentagrophytes in 16 cases, andTrichophyton violaceum in 1 case. Thirty six cases showed negative cultures.In conclusion, the author recommends individual selection of patients for the griseofulvin therapy.     

Keratinolysis by poultry farm soil fungi

Two hundred and eleven dogs (including strictly house and stray dogs) and 170 cattle in and around the city of Madras, India were screened for the presence of dermatophytosis. 106 strains of dermatophytes (89 strains from dogs and 17 strains from bovines) were isolated. 57/106 strains were Trichophyton mentagrophytes var. mentagrophytes and 42/106 strains were of the Microsporum gypseum complex. 5 strains of T. rubrum and 2 strains of T. simii were also obtained in culture. A predominance of M. gypseum complex isolates was recorded in stray dogs and cattle and T. mentagrophytes var. mentagrophytes and T. rubrum in strictly house dogs. The family history of the owners of the most of the dogs had clear records of dermatophytosis. Further, the owners of the 11 dogs that yielded T. mentagrophytes var. mentagrophytes had either tinea corporis or tinea pedis. The etiological agent of all the 11 human cases was T. mentagrophytes var. interdigitale. Similarly the owners of 4 of the 5 dogs that yielded T. rubrum were known T. rubrum patients. All these patients responded to oral griseofulvin or ketaconozole, but the recurrence of lesions was noted with the cessation of treatment. None of the patients had onychomycosis and the family history of all the patients revealed no reports of T. rubrum infections. The pet dogs were presumed to be the source of re-infection. Reversed transmission of dermatophytes from humans to animals may be the reason for the selective predominance of these organisms in strictly house dogs. They also may act as sources of reinfection. Most of the animals had small, occult, scattered lesions. These lesions may either go unnoticed or are ignored by the owners of the animals. The taxonomic status of T. mentagrophytes var. mentagrophytes and T. mentagrophytes var. interdigitale was aligned to their teleomorph Arthroderma vanbreuseghemii. Our study suggests that the periodic screening and medication of all live-stock are essential for the prevention and management of the public health problem caused by dermatophytes. This revised version was published online in August 2006 with corrections to the Cover Date.     

Molecular Approaches in the Diagnosis of Dermatophytosis

Dermatophytosis is one of the most common infectious diseases in the world and can be caused by several dermatophyte species. These species are closely related in genetic structure in spite of different phenotypic and ecological features. The morphological similarity, variability, and polymorphism of dermatophytes have meant that species identification for dermatophytes is time consuming and requires a significant degree of knowledge and technological expertise. Molecular biology-based techniques have solved problems concerning the morphology-based identification of dermatophytes and have improved our knowledge on the epidemiology of dermatophytosis. Further development of molecular diagnosis of dermatophytosis requires the investigation of additional molecular markers for diagnostic tools targeting multiple loci as well as the improvement of techniques.     

126例面癣临床因素及病原菌分析

目的探讨面癣的致病菌种、临床特点及发病相关因素。方法对126例面癣患者进行真菌分离培养鉴定及流行病学分析。结果面癣见于各年龄段,以11～30岁最多见。患病动物接触史、合并其他部位浅部真菌病史及糖皮质类固醇激素类药物外用史是面癣发病的重要危险因素。分离出皮肤癣菌108株,包括红色毛癣菌63株（58．3％）、犬小孢子菌25株（23．1％）、须癣毛癣菌18株（16．7％）和石膏样小孢子菌2株（1．9％）。结论面癣的发病没有年龄差异,患者可见于各个年龄阶段;面癣的常见致病真菌绝大多数为红色毛癣菌和犬小孢子菌,其发病可能与患者自体接种或接触患病动物相关。面癣容易被误诊,及时进行真菌镜检和培养是降低面癣误诊率的关键。     

Epidemiologic study of dermatophyte infections in Nigeria (clinical survey and laboratory investigations)

The commonest dermatophyte infection among the referred dermatology cases in Nigeria is tinea pedis, whereas among the surveyed population of school children, the commonest fungal infection was tinea capitis.It was found that the most ubiquitcus causative organism for tinea pedis was E. fluccosum, that for tinea capitis was M. audouinii, while that for tinea corporis was T. soudanese.The source of infection of tinea capitis among the school children was found to be most likely the local barber who serviced the schools in all the villages, and this might explain the high incidence rate of T. soudanese in tinea capitis. Tinea pedis infection is believed to be highly favoured by the wearing of shoes among the senior students. Animals were not a major source of transmission of dermatophytes in Nigeria.No new species of dermatophytes has been identified among the cultured organisms.     

MALDI‐TOF‐MS‐based species identification and typing approaches in medical mycology

MALDI‐TOF MS‐based species identification has found its place in many clinical routine diagnostic laboratories over the past years. Several well‐established commercial systems exist and these allow precise analyses not only among bacteria, but also among clinically important yeasts. This methodology shows higher precision than biochemical and microscopic methods at significantly reduced turnaround times. Furthermore, the differentiation of different filamentous fungi including most dermatophytes and zygomycetes has been established. The direct identification of yeasts from blood culture bottles will be possible in a routine fashion with new standardized procedures. In addition to species identification, the MALDI‐TOF MS technology offers several further possibilities, like assays to detect or predict resistance phenotypes in fungi as well as subtyping approaches to detect clinically relevant subgroups. The differences between the commercial systems are discussed with respect to fungi and an overview of their performances provided. Factors influencing outcome of MALDI‐TOF‐based species identification are discussed.     

Dermatophyte and non dermatophyte fungi in Riyadh City,Saudi Arabia

BackgroundDermatophytes are a scientific label for a group of three genera (Microsporum, Epidermophyton and Trichophyton) of fungus that causes skin disease in animals and humans. Conventional methods for identification of these fungi are rapid and simple but are not accurate comparing to molecular methods.ObjectiveThis study aimed to isolate human pathogenic dermatophytes which cause dermatophytosis in Riyadh City, Saudi Arabia and to identify these fungi by using conventional and molecular methods.MethodsThe study was conducted in Medical Complex, Riyadh and King Saud University. Samples of infected skin, hairs and nails were collected from 112 patients. Diagnosis of skin infections, direct microscopic test, isolation and identification of dermatophytes by conventional and molecular methods were carried out.ResultsThe results indicated that the tinea capitis infection had the highest prevalence among the patients (22.3%) while Tinea barbae had the lowest. In this study the identified dermatophyte isolates belong to nine species as Trichophyton violaceum, Trichophyton verrucosum, Trichophyton rubrum, Trichophyton mentagrophytes, Trichophyton schoenleinii, Trichophyton concentricum, Microsporum canis, Microsporum audouinii and Epidermophyton floccosum which cause skin infections were isolated during this study. Non dermatophyte isolates included 5 isolates from Aspergillus spp. 4 isolates from Acremonium potronii and 15 isolates from Candida spp. M. canis were the most common species (25% of isolated dermatophytes). Out of the 52 dermatophyte isolates identified by conventional methods, there were 45 isolates identified by the molecular method.ConclusionsThe results concluded that approximately M. canis caused a quarter of dermatophyte cases, tinea capitis infection was prevalent and the molecular method was more accurate than conventional methods.     

New Antifungal Agents and New Formulations Against Dermatophytes

A variety of oral and topical antifungal agents are available for the treatment of superficial fungal infections caused by dermatophytes. This review builds on the antifungal therapy update published in this journal for the first special issue on Dermatophytosis (Gupta and Cooper 2008;166:353–67). Since 2008, there have not been additions to the oral antifungal armamentarium, with terbinafine, itraconazole, and fluconazole still in widespread use, albeit for generally more severe or recalcitrant infections. Griseofulvin is used in the treatment of tinea capitis. Oral ketoconazole has fallen out of favor in many jurisdictions due to risks of hepatotoxicity. Topical antifungals, applied once or twice daily, are the primary treatment for tinea pedis, tinea corporis/tinea cruris, and mild cases of tinea unguium. Newer topical antifungal agents introduced include the azoles, efinaconazole, luliconazole, and sertaconazole, and the oxaborole, tavaborole. Research is focused on developing formulations of existing topical antifungals that utilize novel delivery systems in order to enhance treatment efficacy and compliance.     

Onychomycosis and <Emphasis Type="Italic">Tinea Pedis</Emphasis> in Athletes from the State of Rio Grande Do Sul (Brazil): A Cross-Sectional Study

Onychomycosis and tinea pedis are common superficial infections caused primarily by dermatophytes. The aim of this investigation was to study the epidemiology, etiological agents, and potential risk factors for infection based on comparison of athletes and non-athletes from a northern region of Rio Grande do Sul (Brazil). Each group consisted of 100 male individuals with ages ranging from 18 to 40 years. After a clinical examination, samples were taken from individuals presenting signs of onychomycosis and/or tinea pedis for direct microscopic examination and culture. Among the athletes, the frequency of onychomycosis and/or tinea pedis was 32%, and for the control group, it was 20%. The athletes presented 16% of onychomycosis, 12% of tinea pedis, and 4% of onychomycosis and tinea pedis together. The distribution in the control group was 10% of onychomycosis, 7% of tinea pedis, and 3% of this association. The pathogens identified were dermatophytes (84.8%) and yeasts (15.2%), and the most commonly identified organism was Trichophyton rubrum, followed by Trichophyton mentagrophytes var. interdigitale. No significant differences were found when the frequency of species distribution in the athletes and non-athlete groups was compared. Risk factors for onychomycosis in athletes included familial cases of fungal infection, contact with domestic animals, and nail trauma, while the risk factors in non-athletes included the habit of not using sandals in public bathrooms and nail trauma. For tinea pedis, the habit of not using sandals in public bathrooms was a predisposing factor in both groups, while hyperhydrosis was a risk factor only in non-athletes. This study concludes that despite the higher number of fungal infections in athletes, there is no significant difference between these groups.     

The Epidemiology of Tinea Manuum in Nanchang Area, South China

Tinea manuum is a common superficial fungal infection which is usually coexistent with tinea pedis; there are few studies available on the epidemiology of tinea manuum at present. This study aims to investigate the epidemiology of tinea manuum and its correlation with tinea pedis in south China. A total of 280 patients with tinea manuum were recruited. The epidemiological and clinical data were analyzed, and causative agents were isolated and identified mycologically. Totally, 84.3 % patients with tinea manuum had co-occurrence of tinea pedis, among which 88.4 % patients had experience of scratching their feet. There was a significant relationship between the touch habits and the hand infection (χ² = 65.451, P = 0.000). More than 90 % patients had quite the same species of isolates from multiple infected sites in one patient. Therefore, it seems that transmission of dermatophytes from the feet to hand by scratching might be a most common way. As for tinea manuum, whether “unilateral” or “bilateral” is just the result that pathogens spread from feet to hand(s), which is only a special clinical presentation of tinea.     

Prevalence of dermatophytes and yeasts (Candida spp., Malassezia furfur) in HIV patients

The prevalence of dermatophytes and yeasts (Candida spp. and Pityrosporum spp.) was studied in 40 former drug-addicts, all of whom were HIV seropositive but otherwise had no other symptoms (2nd Stage CDC Atlanta, 1987). We considered 7 skin areas for dermatophytes and Pityrosporum spp. (scalp, forehead, nose, back, chest, groin, toe webs) and the mouth for yeasts. Dermatophytes were found in 8 (20%) and tinea pedis was the most common dermatophytosis: Tricophyton rubrum was the fungus most frequently isolated (6 cases or 15%). The HIV + group showed almost the same rate of dermatophytes colonisation compared to a group of 121 athletes and to the control group. Candida spp. was present in 27 cases (67.5%) but clinical oral lesions were evident only in 5 patients (12.5%). Statistically significant differences were found in the presence of Candida spp. in HIV patients and controls (p<0.05). The lipophilic yeast Pityrosporum ovale was evaluated with quantitative and qualitative methods. Quantitative variations were evident between HIV patients and controls. P. ovale was present in 10 cases: 3 (7.5%) of them showed dischromic lesions while in 7 cases (17.5%) no clinical symptoms were evident.     

Trapped in keratin; a comparison of dermatophyte detection in nail, skin and hair samples directly from clinical samples using culture and real-time PCR

Traditionally, laboratory detection and identification of dermatophytes consists of culture and microscopy which yields results within approximately 2-6 weeks. In 2007 our medical microbiological diagnostic laboratory implemented a molecular method for the detection of dermatophytes. A real-time PCR assay was developed which simultaneously detects and identifies the most prevalent dermatophytes directly in nail, skin and hair samples and has a turnaround time of less than two days. For 1437 clinical samples, received by our diagnostic laboratory, we compared the results obtained from both culture and real-time PCR. This study showed that real-time PCR significantly increased the detection rate of dermatophytes compared to culture. Furthermore, excellent concordance between culture and real-time PCR identification was achieved.