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.