A Cross-sectional Study Comparing the in vitro Biofilm Optical Density of Dermatophytic Isolates with Clinical Profile, Risk Factors, and Antifungal Susceptibility.

Background: In India, Trichophyton mentagrophytes has emerged as the dominant cause of dermatophytosis, surpassing Trichophyton rubrum, contributing to an epidemic-like surge in cases. The Indian genotype "T. mentagrophytes ITS genotype VII" exhibits widespread resistance to terbinafine due to mutations in the squalene epoxidase gene. Rising instances of recurrent and chronic dermatophytosis highlight the urgent need to explore factors like host profiles, environmental influences, and antifungal resistance, including the role of biofilms. Objective: This study aimed to evaluate biofilm formation in dermatophyte isolates and explore its correlation with demographic factors, disease duration, steroid misuse, and antifungal resistance to facilitate future management strategies. Materials and Methods: A total of 65 patients with clinically diagnosed dermatophytosis were included in this tertiary care center-based study. Detailed clinical histories were documented, and biofilm formation was quantified using crystal violet staining. Antifungal susceptibility testing was performed according to CLSI M38-A2 guidelines. Clinical improvement was assessed using the Clinical Assessment Severity Score, and statistical analysis was performed to explore associations between biofilm formation, clinical response, and antifungal resistance. Results: T. mentagrophytes/Trichophyton interdigitale complex was identified in 98.46% of cases, with significant antifungal resistance to fluconazole and griseofulvin. The mean biofilm optical density was significantly higher in isolates from patients using oral antifungal treatments, especially those with poor clinical responses. Biofilm density was also significantly associated with antifungal resistance, particularly against fluconazole and griseofulvin (P < 0.001). Conclusion: Our findings underscore the role of biofilm formation in contributing to chronic and recurrent dermatophytosis, particularly in patients with a history of oral antifungal use. Biofilm density correlates significantly with antifungal resistance, which may hinder clinical outcomes. These results highlight the need for tailored treatment strategies targeting biofilm-associated resistance to improve the management of chronic dermatophytosis.