Antifungal Susceptibility and Biofilm Formation in Dermatophytes from Chronic and Recurrent Dermatophytosis: Correlation with Treatment Failure

Abstract

Background: In India, dermatophytosis has become a serious public health issue due to an increasing number of cases that develop into chronic or recurrent illnesses that do not respond well to conventional antifungal treatment. Treatment failure is thought to be largely caused by shifting dermatophyte species epidemiology, growing antifungal resistance, and possible contributing variables including biofilm formation. However, there is still a dearth of systematic data, especially in eastern India, linking antifungal susceptibility patterns, biofilm-forming capacity, and clinical outcomes.

Objectives: The objective of this study was to analyze the biofilm-forming capacity and antifungal susceptibility profile of dermatophyte isolates from patients with recurrent and chronic dermatophytosis, as well as their association with treatment failure that has been recorded.

Methods: Between February 2023 and January 2024, a prospective cross-sectional study was carried out at Nalanda Medical College and Hospital in Patna. A total of 200 patients with clinically diagnosed chronic or recurrent dermatophytosis were enrolled. Fungal culture and direct microscopy were applied to clinical specimens. Phenotypic techniques were used to identify dermatophyte isolates, and when necessary, genetic confirmation was obtained. A standardized broth microdilution approach was employed for antifungal susceptibility testing to ascertain the minimum inhibitory concentrations (MICs) for frequently used antifungal drugs. Using a microtiter plate crystal violet assay, biofilm production was evaluated and classified as weak, moderate, or strong. To investigate correlations with treatment failure, clinical and laboratory indicators were examined.

Results: A significant percentage of cases had dermatophytes identified, with species from the Trichophyton mentagrophytes/interdigitale complex predominating. Terbinafine and fluconazole often showed high minimum inhibitory concentrations (MICs), while more recent azoles showed relatively lower MICs. A considerable percentage of isolates demonstrated moderate to strong biofilm-forming ability. Strong biofilm producers were strongly linked to previous treatment failure and were more likely to have increased MICs.

Conclusion: The research reveals a worrying pattern of decreased antifungal susceptibility in dermatophytes that cause recurring and chronic dermatophytosis. Antifungal resistance and treatment failure seem to be significantly influenced by biofilm development. Incorporating biofilm evaluation and antifungal susceptibility testing into standard diagnostic procedures may assist direct more successful treatment approaches and enhance patient outcomes.

Keywords: Dermatophytosis, Antifungal susceptibility, Biofilm formation, Chronic dermatophytosis, Treatment failure