Antifungal Susceptibility Pattern of Non - Dermatophytic Fungi Causing Onychomycosis

Abstract

Introduction: Non-dermatophytic molds (NDM) are filamentous fungi or yeast, commonly found in nature as saprophytes and plant pathogens. The incidence of onychomycosis due to NDM is 1.45 – 16.6%. NDMs are usually resistant to conventional antifungal treatment.

Objective: To know the anti-fungal susceptibility pattern of non-dermatophyte fungi causing onychomycosis. 

Materials and Methods: A prospective hospital based cross-sectional study was done on non - dermatophytic isolates from patients with clinical suspicion of onychomycosis. All non – dermatophytic isolates were subjected to anti-fungal susceptibility against terbinafine, itraconazole, fluconazole and griseofulvin by micro broth dilution method. 

Results: NDM were isolated in 20.2% cases of clinically suspected onychomycosis, among which Fusarium species was the most common followed by Aspergillus species and Candida species. MIC50 (Mean Inhibitory Concentration) for overall non - dermatophytic isolates for terbinafine, itraconazole, fluconazole and griseofulvin was 0.25μg/mL, 0.5μg/mL, 32μg/mL and 2μg/mL respectively and the order of sensitivity was Itraconazole (74.7%) > terbinafine (68%) > Fluconazole (60%) > Griseofulvin (51.6%) of the study samples. For Fusarium species, the  sensitivity for terbinafine was (73.5%) > itraconazole (67.6%) > fluconazole (64.7%) and griseofulvin (64.7%). For Aspergillus species, the sensitivity for itraconazole was 79.1% > fluconazole (58.3%) > terbinafine (54.1%) > griseofulvin (50%). For Candida species, the sensitivity was fluconazole (83.3%) > itraconazole (75%) > terbinafine (41.6%), while no candida species was found sensitive to griseofulvin. 

Conclusion: Non-dermatophytes play a significant role in onychomycosis. On in vitro estimation, Itraconazole was the most sensitive drug, followed by terbinafine, fluconazole and griseofulvin.