Background and objectives: Black Aspergillus strains including, Aspergillus niger and A. tubingensis, are the most cause of otomycosis with worldwide distribution. Although, amphotericin B was a Gold standard for the treatment of invasive fungal infection for several decades, it gradually replaced by fluconazole and /or voriconazole. Moreover, luliconazole, appears to offer the best potential for in vitro activity against black Aspergillus strains. The aim of the present study was to compare the in vitro activity luliconazole, with commonly used antifungals against clinical and environmental strains of black Aspergillus.

Materials and methods: Sixty seven (37 clinical and 30 environmental) strains of black Aspergillus were identified using morphological and molecular technique (β-Tubulin gene). In addition, antifungal susceptibility test was applied according to CLSI M38 A2. The results were reported as minimum inhibitory concentration (MIC) or minimum effective concentration (MEC) range, MIC₅₀ or MEC₅₀, MIC₉₀ or MEC₉₀ and MIC geometric (GM) or MECGM.

Results: Aspergillus niger was the common isolate followed by, A. tubingensis in both clinical and environmental strains. The lowest MIC range, MIC₅₀, MIC₉₀, and MICGM was attributed to luliconazole in clinical strains. The highest resistant rate was found in amphotericin B for both clinical (86.5%) and environmental (96.7%) strains whereas 54.1% of clinical and 30% of environmental isolates were resistant to caspofungin. Clinical strains of Aspergillus were more sensitive to voriconazole (86.7%) than environmental strains (70.3%). On the other hand, 83.8% of clinical and 70% of environmental isolates were resistant to posaconazole.

Conclusion: Luliconazole versus amphotericin B, voriconazole, posaconazole and caspofungin is a potent antifungal for Aspergillus Nigri complex. The in vitro extremely antifungal efficacy against black Aspergillus strains of luliconazole, is different from those of other used antifungals.