Comparative Analysis of Antifungal Susceptibility in Trichophyton Species Using Broth Microdilution Assay: A...

Background Dermatophyte infections, predominantly caused by Trichophyton species, are a global health concern, particularly in tropical regions. The rising prevalence of resistant strains, due to the misuse of antifungal agents, necessitates robust antifungal susceptibility testing. This study aimed to evaluate antifungal susceptibility patterns of clinical isolates using the broth microdilution (BMD) assay to guide treatment strategies effectively. Methods A cross-sectional study was conducted at the All India Institute of Medical Sciences (AIIMS), Rishikesh, for over two years, including 184 clinical samples from patients with recalcitrant dermatophytosis. Samples were collected aseptically, and antifungal susceptibility testing was performed using the BMD assay. Minimum inhibitory concentration (MIC) values were analyzed for five drugs: amphotericin, terbinafine, griseofulvin, itraconazole, and fluconazole. Associations with patient demographics, potassium hydroxide (KOH) positivity, and culture outcomes were statistically assessed. Results Amphotericin showed the lowest mean MIC (0.57 µg/mL), while fluconazole exhibited the highest (7.70 µg/mL). Amphotericin and terbinafine achieved 100% inhibition, while other drugs showed 80% inhibition. Gender had no significant effect on MIC values. KOH positivity and culture outcomes significantly influenced MICs, with species-specific patterns observed. For instance, T. mentagrophytes and T. indotineae were linked to higher MICs for fluconazole and griseofulvin. Conclusion The study underscores the need for species-specific antifungal susceptibility testing to monitor resistance trends. Results focused on unexpected resistance to typically effective drugs like terbinafine or fluconazole. Routine testing and targeted stewardship are essential to improve therapeutic outcomes for dermatophytosis.