Discussion
Dermatophytosis is considered a mild skin infection that is prevalent throughout the world. The availability of various effective antifungal treatments have made the management of dermatophytosis feasible and effective. In India, a surge in the number of resistant fungal infections has become a major health concern and termed the “Indian epidemic” (2) . Resistance to terbinafine in India has been well studied using molecular identification, phylogenetic analysis, in vitro susceptibility testing, and SQLE gene analysis. In 2018, Singh et al presented a series of 20 terbinafine-resistant T. interdigitale isolates obtained predominantly from cases of tinea corporis and tinea cruris in Delhi, India (3). A 2018 in-vitro study in India also shows antifungal resistance to griseofulvin (4). In the past three years, we see the emergence of dermatophyte infections resistant to antifungals in Pakistan and America as well (1,2). In Northern and Western Pakistan, studies report resistance to fluconazole but no resistance to nystatin (5). In this region of Pakistan, the prevalence of resistance was greater among male children in rural areas (5). In the Southern Punjab province of Pakistan, resistance to azole and polyene has been documented, most prevalent amongst females aged 21 to 30 years old (6). The one reported case of treatment-resistant T. corporis in the United States shows resistance to terbinafine but sensitivity to fluconazole, griseofulvin, and itraconazole (1).
In-vitro resistance to antifungals can be due to primary or secondary causes. Primary resistance occurs when an organism has an intrinsic, natural resistance to the antifungal. Secondary resistance occurs after the organism has been exposed to the antifungal and acquires resistance by undergoing specific mutations (2). A 2018 in-vitro study in India used broth microdilution assay for dermatophytes antifungal susceptibility testing and recorded MIC50 and 90 values for terbinafine, fluconazole, itraconazole, ketoconazole, voriconazole, and amphotericin B. The results of this study concluded that tinea corporis treatment failure may be attributable to the intrinsic virulence of dermatophytes species and the host fungal interaction that helps fungi evade immune response from the host, rather than to secondary antifungal resistance (7). Therefore, they recommend the terminology “recalcitrant infection” rather than “resistant cases.” Similar in-vitro studies and antifungal susceptibility testing should be performed in Pakistan and other parts of the world so that the exact cause of treatment failure can be elucidated and addressed. Dermatophytoses casued by resistant Trichophyton indotineae stains have been observed in parts of Europe. These strains were initially detected in India and later spread to other parts of South Asia (8). Besides resistance to cutaneous fungal infection, resistance to invasive fungi was also observed during the COVID-19 pandemic and it was responsible for increased morbidity and mortality in patients suffering from COVID-19 in India (9). Resistance in cases of invasive fungi during the pandemic was attributable to injudicious use of medications (9).
Resistant cases will demand expensive care at more equipped healthcare facilities and invasive antifungal therapies that were once reserved for immunocompromised patients, which will inevitably be accompanied by additional side effects. Newer antifungals will need to be developed to combat resistant cases. This case report aims to increase awareness amongst dermatologists and researchers about the ensuing public health crisis of treatment-resistant tinea corporis infections that are currently disproportionately affecting skin of color and demonstrate the potential of targeting socioeconomically disadvantaged communities.