Clinical, Dermoscopic, and Mycological Evaluations of Resistant Dermatophytosis

Fungal Skin Infection, Tinea Corporis

Dermatophytosis, resistance, PCR, antifungal

Dermatophytosis is a common superficial infection of the skin, hair, or nails caused by dermatophyte, it is colloquially known as ringworm or tinea infection and affects an estimated one in five people in their lifetime

According to surveys conducted by the World Health Organisation, it has been found that approximately 25% of the global population is impacted by dermatophytes. Males are more likely to have dermatophytosis infections caused by the physiological structure of males who are more active outdoors and demand physical activity to provide conditions conducive to the growth of dermatophytes . On the other hand, female is less likely to be infected with dermatophytes, which is associated with their lifestyle, including a lot of housework, indoor activities, and hormonal factors. Dermatophytosis is a multifactorial disease influenced by the interaction of host, environmental, and behavioral factors. Major risk factors include hot and humid climates, excessive sweating, poor personal hygiene, the use of occlusive clothing or footwear, overcrowding, and low socioeconomic status . In addition, close contact with infected individuals, contaminated fomites, or infected animals facilitates disease transmission. Certain medical conditions, including diabetes mellitus, obesity, peripheral vascular disease, and immunosuppression, increase susceptibility to infection by impairing host defense mechanisms. Dermatophytosis spreads easily among persons and animals, and by shared objects or surfaces such as clothing and locker room floors. Its more predominant in the tropical and subtropical countries; especially in the developing countries where hot climate and humid weather is favorable to the acquisition and maintenance of the disease. The causative organisms of these infections can be classified based on their ecological niche: anthropophilic species, which primarily infect humans; zoophilic species, which originate from animals; and geophilic species, which are found in soil. The most common causative organisms affecting humans belong to the genera ;Trichophyton, Microsporum, and Epidermophyton . Trichophyton rubrum is the most common causative agent in high income countries, and Trichophyton mentagrophytes species complex, Microsporum canis, and Epidermophyton floccosum are most prevalent globally. Trichophyton schoenleinii, Trichophyton soudanese, and Trichophyton concentricum are generally limited to parts of Europe, Asia, and Africa . Classically, dermatophytosis affecting the skin causes a characteristic red, scaly, itchy, ring-shaped lesion with central clearing. Historically, clinicians and laboratory scientists have viewed dermatophytosis as a mild condition meriting less attention compared with invasive, life-threatening infections such as candidemia and invasive pulmonary aspergillosis . However, the epidemiology of dermatophytosis has changed dramatically in the last decade because of the emergence of dermatophyte strains causing infections that are increasingly severe and difficult-to-treat The reasons for the emergence of resistant strains have not been fully researched, but in India, potent steroid creams combined with antifungal agents and antimi-crobial agents are freely available and have been sold in large quantities over the counter. These preparations actually being cheaper than pure antifungal agents mean they are the often first choice for consumers . The misuse of antifungal agents, over-the-counter available antimycotics, patient non-compliance, treatment combinations of antifungals with topical steroids, as well as changes relative to travel and migration, all are contributing factors to a global increase in antifungal resistance . In the last few years, awareness has been raised internationally about the growing threat of fungal resistance to common antifungal agents. Globally, Trichophyton rubrum is the most frequently identified cause of dermatophytosis. However, Trichophyton indotineae (T. indotineae), a newly identified species within the Trichophyton mentagrophytes complex, has recently emerged as the predominant pathogen in India and other parts of Asia. T. indotineae exhibits an anthropophilic instead of a zoophilic transmission pattern and has developed a high level of terbinafine resistance . Due to globalization, this new emerging pathogen has been isolated in many countries outside Asia, causing an epidemic of severe, recalcitrant dermatophytosis. Patients with these infections can present with double-edged or multiedged tinea concentric scaly rings. Large lesions with multiple, closely juxtaposed, centrifugally spreading lesions with eczematous centers have also been described , and have frequent relapses and treatment failures due to antifungal resistance, including resistance to terbinafine and the azoles itraconazole and voricon. Diagnostic testing for suspected dermatophyte infections is important to help minimize overuse and incorrect use of antifungal drugs, which may contribute to resistance development . Unfortunately, diagnostic testing may be disincentivized due to low reimbursement rates, long turnaround times, and Clinical Laboratory Improvement Amendments (CLIA)-related restrictions on in-office microscopy . These gaps might be addressed through increased adoption of polymerase chain reaction (PCR)-based testing to identify dermatophyte species and development of rapid, accurate, and affordable point-of-care tests for dermatophyte identification.

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