Deep facial mycosis due to Trichophyton verrucosum-molecular genetic identification of the dermatophyte in paraffin-embedded tissue-case report and review of the literature

[Clinical picture, causative agents and diagnostics of dermatomycoses]

Dermatomycoses affect free skin, hairy scalp, fingernails and toenails. In addition, oral mucosa and genital mucosa can also be affected by fungal infections. The most common pathogens causing skin fungal infections are dermatophytes. They are responsible for, among others, tinea corporis, tinea capitis and onychomycosis (tinea unguium). Mainly anthropophilic dermatophytes are found as pathogens. In the case of tinea capitis-at least in Europe and in German-speaking countries-zoophilic skin fungi must also be considered. Rarely, geophilic dermatophytes can also be isolated. Yeast infections of the skin, mostly caused by Candida albicans, primarily affect the intertriginous skin areas, for example, the groin region, but also the submammary area and the spaces between the fingers and toes. Elderly patients are often affected, but also infants and, in particular, immunocompromised patients. These patient groups are also more frequently affected by oral mucosal infections caused by Candida albicans and other Candida species. Pseudomembranous candidiasis of the oral mucosa and tongue typically affects patients with HIV/AIDS. Mold infections in dermatology are relevant in onychomycosis of the big toenail. The causative agent is usually Scopulariopsis brevicaulis. Cutaneous mold infections are rare and only occur in immunocompromised patients. The mycological diagnosis of dermatomycoses is based on the microscopic, if possible fluorescence-optical detection of fungal hyphae and spores from skin scales, nail shavings and hair roots. The culture detection of dermatophytes, yeasts and molds allows the identification of the causative fungal species, but often fails, especially in patients who have already been treated with antifungal agents. In view of the high sensitivity and specificity of the molecular methods for fungal detection compared to culture, polymerase chain reaction (PCR) must realistically be regarded as the gold standard for dermatophytosis diagnostics. However, it should not be neglected that the three pillars of diagnostics-preparation, culture, PCR-currently deliver the best results.

Human and Zoonotic Dermatophytoses: Epidemiological Aspects

Introduction

Dermatophytes are a group of molds characterized by the ability to produce keratinases, thereby carving out for themselves specific ecological niches. Their traditional division into three genera, Trichophyton, Microsporum, and Epidermophyton has been expanded to nine and the species in each genus were modified. Dermatophytes are among the most prevalent causes of human and animal mycoses. Their epidemiology is influenced by various factors. These factors may be evolutive such as the predilected environment of the fungus, namely, humans (anthropophilic), animals (zoophilic), or environment (geophilic), is evolutionary and thus may require centuries to develop. Many other factors, however, result from a variety of causes, affecting the epidemiology of dermatophytoses within a shorter time frame.

Objective

This review aims at summarizing the factors that have modified the epidemiology of dermatophytoses during the last decades.

Results

Geographic and climatic conditions, demography such as age and gender, migration, socio-economic conditions, lifestyle, and the environment have had an impact on changes in the epidemiology of dermatophytoses, as have changes in the pattern of human interaction with animals, including pets, farm, and wild animals. A typical example of such changes is the increased prevalence of Trichophyton tonsurans, which spread from Latin America to the United States and subsequently becoming a frequent etiological agent of tinea capitis in Africa, Middle East, and other areas.

Conclusion

The comprehension of the epidemiology of dermatophytoses has a major bearing on their prevention and treatment. Since it is undergoing continuous changes, periodic assessments of the most recent developments of this topic are required. This article aims at providing such an overview.

Ringworm in calves: risk factors, improved molecular diagnosis, and therapeutic efficacy of an Aloe vera gel extract

Background

Dermatophytosis in calves is a major public and veterinary health concern worldwide because of its zoonotic potential and associated economic losses in cattle farms. However, this condition has lacked adequate attention; thus, to develop effective control measures, we determined ringworm prevalence, risk factors, and the direct-sample nested PCR diagnostic indices compared with the conventional methods of dermatophytes identification. Moreover, the phenolic composition of an Aloe vera gel extract (AGE) and its in vitro and in vivo antidermatophytic activity were evaluated and compared with those of antifungal drugs.

Results

Of the 760 calves examined, 55.79% (424/760) showed ringworm lesions; 84.91% (360/424) were positive for fungal elements in direct-microscopy, and 79.72% (338/424) were positive in culture. Trichophyton verrucosum was the most frequently identified dermatophyte (90.24%). The risk of dermatophytosis was higher in 4–6-month-old vs. 1-month-old calves (60% vs. 41%), and in summer and winter compared with spring and autumn seasons (66 and 54% vs. 48%). Poor hygienic conditions, intensive breeding systems, animal raising for meat production, parasitic infestation, crossbreeding, and newly purchased animals were statistically significant risk factors for dermatophytosis. One-step PCR targeting the conserved regions of the 18S and 28S genes achieved unequivocal identification of T. verrucosum and T. mentagrophytes in hair samples. Nested-PCR exhibited an excellent performance in all tested diagnostic indices and increased the species-specific detection of dermatophytes by 20% compared with culture. Terbinafine and miconazole were the most active antifungal agents for dermatophytes. Gallic acid, caffeic acid, chlorogenic acid, cinnamic acid, aloe-Emodin, quercetin, and rutin were the major phenolic compounds of AGE, as assessed using high-performance liquid chromatography (HPLC). These compounds increased and synergized the antidermatophytic activity of AGE. The treated groups showed significantly lower clinical scores vs. the control group (P < 0.05). The calves were successfully treated with topical AGE (500 ppm), resulting in clinical and mycological cure within 14–28 days of the experiment; however, the recovery was achieved earlier in the topical miconazole 2% and AGE plus oral terbinafine groups.

Conclusions

The nested PCR assay provided a rapid diagnostic tool for dermatophytosis and complemented the conventional methods for initiating targeted treatments for ringworm in calves. The recognized antidermatophytic potential of AGE is an advantageous addition to the therapeutic outcomes of commercial drugs.

Berufliche Infektion mit Trichophyton verrucosum bei einem Rinderzüchter

Die Kälberflechte ist eine durch Tiere übertragene Pilzinfektion, die berufsbedingt auftreten und nach Nr. 3102 BKV (Berufskrankheiten-Verordnung) als Berufskrankheit anerkannt werden kann. Die durch Trichophyton verrucosum ausgelöste Zoonose zeichnet sich häufig durch einen schweren klinischen Verlauf aus, der nicht selten als bakterielle Infektion fehlgedeutet und primär antibiotisch behandelt wird. Die Gewinnung und mykologische Untersuchung von Schuppenmaterial ist diagnostisch entscheidend; auch eine Biopsie kann wegweisend sein. Die orale Therapie erfolgt leitliniengemäß mit Terbinafin. Zudem ist zum Schutz vor Reinfektionen auf besondere Hygienemaßnahmen in Ställen zu achten.

[Dermatophytosis caused by rare anthropophilic and zoophilic agents]

The basis for effective treatment of any dermatomycosis is the correct and timely identification of the pathogen, which allows the targeted choice of the most suitable antimycotic and is important for the prevention of repeated infections. In recent years, infections with dermatophytes seem to have increased. In fact, from 2007 to 2018, there was an increase in the number of samples processed in the Mycology Laboratory of the Department of Dermatology at the University Hospital Jena. The most common isolated dermatophytes between 2007 and 2018 were Trichophyton (T.) rubrum, T. interdigitale, Microsporum (M.) canis and T. benhamiae. However, dermatophytoses may also be caused by rare anthropophilic agents such as Epidermophyton floccosum, zoophiles such as T. verrucosum, T. quinckeanum or Nannizzia (N.) persicolor as well as by geophiles such as N. gypsea. Therefore, these dermatophytes should at least be known, so that in case of unusual observations investigations can be performed accordingly. Changes in the pathogen spectrum of dermatophytoses have taken place over time and it is expected that the occurrence of dermatophytes will be subject of continuous fluctuations, which may mean that the incidence of some of these "rare" dermatophytes, as described here in five clinical examples, may be changing.

[Tinea barbae profunda due to Trichophyton mentagrophytes : Case report and review]

Tinea barbae is a rare dermatomycocis, by definition follicular bound in the beard area of adult men. Manifestation usually starts with erythema accompanied by desquamation. Deeper distribution along terminal hairs leads to folliculitis with formation of pustules and nodes as well as abscesses; fixed adherent yellowish crusts may appear. Frequently there is locoregional swelling of the lymph nodes and occasionally a deterioration of general condition with (sub)febrile temperatures. Often this leads to the initial suspected diagnosis of a bacterial folliculitis barbae or impetigo contagiosa. Tinea barbae is mostly induced by species of the genus Trichophyton (T.). The pathogens are diverse and are mostly zoophilic, sometimes anthropophilic and rarely geophilic dermatophytes. With the help of a specific anamnesis and diagnostic procedure, including mycological examinations, histology and molecular detection of dermatophytes via polymerase chain reaction (PCR), tinea barbae-in our patient induced by T. mentagrophytes-can be rapidly diagnosed. Early initiation and adequate treatment duration lead to restitutio ad integrum.