From Animal to Man: Tinea Barbae

Expert Panel Review of Skin and Hair Dermatophytoses in an Era of Antifungal Resistance

Dermatophytoses are fungal infections of the skin, hair, and nails that affect approximately 25% of the global population. Occlusive clothing, living in a hot humid environment, poor hygiene, proximity to animals, and crowded living conditions are important risk factors. Dermatophyte infections are named for the anatomic area they infect, and include tinea corporis, cruris, capitis, barbae, faciei, pedis, and manuum. Tinea incognito describes steroid-modified tinea. In some patients, especially those who are immunosuppressed or who have a history of corticosteroid use, dermatophyte infections may spread to involve extensive skin areas, and, in rare cases, may extend to the dermis and hair follicle. Over the past decade, dermatophytoses cases not responding to standard of care therapy have been increasingly reported. These cases are especially prevalent in the Indian subcontinent, and Trichophyton indotineae has been identified as the causative species, generating concern regarding resistance to available antifungal therapies. Antifungal-resistant dermatophyte infections have been recently recognized in the United States. Antifungal resistance is now a global health concern. When feasible, mycological confirmation before starting treatment is considered best practice. To curb antifungal-resistant infections, it is necessary for physicians to maintain a high index of suspicion for resistant dermatophyte infections coupled with antifungal stewardship efforts. Furthermore, by forging partnerships with federal agencies, state and local public health agencies, professional societies, and academic institutions, dermatologists can lead efforts to prevent the spread of antifungal-resistant dermatophytes.

Current Topics in Dermatophyte Classification and Clinical Diagnosis

Dermatophytes are highly infectious fungi that cause superficial infections in keratinized tissues in humans and animals. This group of fungi is defined by their ability to digest keratin and encompasses a wide range of species. Classification of many of these species has recently changed due to genetic analysis, potentially affecting clinical diagnosis and disease management. In this review, we discuss dermatophyte classification including name changes for medically important species, current and potential diagnostic techniques for detecting dermatophytes, and an in-depth review of Microsporum canis, a prevalent zoonotic dermatophyte. Fungal culture is still considered the “gold standard” for diagnosing dermatophytosis; however, modern molecular assays have overcome the main disadvantages of culture, allowing for tandem use with cultures. Further investigation into novel molecular assays for dermatophytosis is critical, especially for high-density populations where rapid diagnosis is essential for outbreak prevention. A frequently encountered dermatophyte in clinical settings is M. canis, which causes dermatophytosis in humans and cats. M. canis is adapting to its primary host (cats) as one of its mating types (MAT1-2) appears to be going extinct, leading to a loss of sexual reproduction. Investigating M. canis strains around the world can help elucidate the evolutionary trajectory of this fungi.

[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.

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

Deep trichophytosis is relatively uncommon. The infection of the bearded area is also known as sycosis barbae or tinea barbae and can be caused by various fungal species, most often zoophilic fungi. We report on an 80-year-old male patient with severe sycosis barbae who had no animal contact and was treated with systemic antibiosis without improvement. Microbial and mycological investigations using swabs from oozing lesions revealed Staphylococcus haemolyticus and Candida parapsilosis. Histology demonstrated fungal elements in hair follicles. Paraffin-embedded material was subjected to further mycological analysis. For molecular diagnostics DNA was prepared from paraffin sections for real-time polymerase chain reaction (RT-PCR). For sequencing, DNA was isolated from paraffin-embedded skin tissue and the ITS region of the rDNA was selected. Sequencing of the ITS2 region of rRNA revealed a 100% accordance with Trichophyton (T.) verrucosum. Treatment with oral terbinafine achieved a complete remission. Sycosis barbae is an important differential diagnosis for infections of the bearded area. Nucleic acid amplification techniques (NAAT) are more and more used for direct examination of dermatophytes in clinical samples, eg T. verrucosum. NAAT are also used as culture confirmation tests for identification of rare dermatophytes like T. verrucosum. Today, singleplex and multiplex quantitative real-time PCR (qRT-PCR) assays for the detection of the most common dermatophytes including T. verrucosum in clinical specimens are available. Recently, an ITS2 PCR assay has been successfully used for direct detection of T. verrucosum in paraffin-embedded formalin-fixed skin tissue. The PCR is fast and highly specific. The sensitivity of direct molecular detection of the dermatophytes both in native clinical material, and in paraffin-embedded skin tissue can been increased.

A facial swelling with multiple discharging sinuses: a diagnostic conundrum

BACKGROUND

Many disease processes can present with facial swelling and multiple discharging sinuses. A differential diagnosis would include actinomycosis, tuberculosis and osteomyelitis, but tinea barbae is a relatively uncommon presentation.

CASE REPORT

The following case report describes a 48-year-old jockey who was diagnosed with tinea barbae. It chronicles the investigations that were performed to determine the offending pathogen and the difficulty in achieving a diagnosis.

DISCUSSION

The investigations and the pathophysiology of dermatophytic infections and their management in a maxillofacial/oral medicine environment are discussed.

High infection rate of Trichophyton verrucosum in calves from Central Italy

Recent epidemiological features of the zoonotic dermatophyte Trichophyton verrucosum were investigated in 294 calves from 20 farms located in Central Italy. By the combination of microscopic examinations and fungal cultures, the total prevalence rate of T. verrucosum infection was found to be high, with 87.7% of samples yielding positive results and 100% of farms being infected. Farm to farm prevalence of infection varied from 25% to 100% of the examined calves. Prevalence rates were higher in females than males (91.6% versus 84%), in >3-< or =6 than >6-< or =9 month old calves (89.8% versus 85.7%), in purebred than in crossbred (88.5% versus 81.8%), and in symptomatic than asymptomatic ones (95.7% versus 80.4%). T. verrucosum was as prevalent in semi-intensive as in intensive breeding system (88.2% versus 87.6%) but more prevalent in calves raised for meat rather than milk production (91.1% versus 84.9%), and reared under conventional than organic production management system (89.3% versus 82.6%). Prevalence rates were also higher when the cattle present in the farm were of mixed origin, rather than when the whole stock was purchased or was born in the farm (92% versus 88.2% and 85.7%), when other cattle in the farm were showing skin signs (90% versus 84.2%), and at least one case of human ringworm was recorded in the farm (90.9% versus 86.1%). No statistically significant association was found. Therefore, T. verrucosum infection may be more widespread in calves from Central Italy than it was previously thought to be. Calves of any sex, breed, age, and of any of the farm condition considered, are highly exposed to the risk of infection. As calves may play a considerable role as reservoirs of the infection, our results highlight the need to determine the incidence and the importance of T. verrucosum ringworm in personnel involved with cattle care in Italy and elsewhere.

Dermatophytoses in forestry workers and farmers

To assess the frequency of superficial mycoses in forestry workers and farmers in the rural region of Duzce, a total of 467 residents of the rural region were examined for dermatomycosis infection. Of these, 349 were forestry workers and 118 farmers. All specimens collected were analysed by direct microscopy and culture. Tinea pedis et manus was found in 23 (19.4%), and onycomycosis in 21 (17.7%) farmers. Tinea pedis et manus was found in 50 (14.3%), and onycomycosis in 28 (8%) forestry workers. One tinea corporis, two tinea inguinalis and two erosio interdigitalis cases were determined in the farmer group but no cases of tinea corporis, tinea inguinalis, or erosio interdigitalis were found in the forestry group. In total, five tinea versicolor cases were found in the two groups on clinical examination but no agent positivity was yielded in mycological cultures. The most frequently isolated agent in the two groups was Trichophyton rubrum. The frequencies of superficial mycosis and onychomycosis were found to be higher in the farmer group than in the forestry group, although similar aetiological agents were isolated in both groups. The farmers had greater rates of contact with pathogenic fungi present in soil as well as from infected farm animals than the foresters; furthermore, animal husbandry, and the wearing of rubber shoes and nylon socks were more frequent in the farmer group. These results suggest that habits such as the wearing of rubber shoes and nylon socks, and the practice of animal husbandry may be the most important factors in determining the frequency of superficial mycoses and aetiological agents in forestry workers and farmers. To our knowledge, there is no previous report about dermatophytoses in forestry workers.

Dermatophytes in the rural area of Duzce, Turkey

A total of 227 subjects (112 were male and 115 female), who were residents of the rural region of Duzce, were examined for dermatomycosis. A total of 120 samples (47 nail fragments, 73 skin scales) were collected from 81 patients for mycological analysis on the basis of the results of clinical evaluation. All specimens collected were analysed by direct microscopy and culture. Positive results were detected in the cultures of 53 (44.1%) of the 120 samples. About 46 (86.7%) samples also presented positive results in direct microscopy. In the cases of seven samples positive results were found in culture and negative results with direct microscopy. Both culture and direct microscopy presented negative results in 67 (55.8%) samples. The most frequently isolated aetiological agents were 33 Trichophyton rubrum (62.2%), and nine T. mentagrophytes (16.9%). In conclusion, traditional and religious habits such as cohabitation and performing ritual ablutions may affect the prevalence of dermatophyte infections. The performance of ritual ablutions is not in itself a risk factor for acquiring dermatophyte infection; rather it is not drying the extremities after ablutions, that is the main risk factor for this group. Tinea capitis was not found in any of the subjects in spite of the fact that it is one of the most common infectious conditions in children. This is the first paper to report the prevalence of fungal infections in Duzce, a western Black Sea region of Turkey.