Evaluation of Drug Susceptibility of Aspergillus Species Isolated from Patients with Otomycosis in Vitro

Otomycosis is a chronic, acute or subacute infection of the external auditory canal. Aspergillus and Candida species are the most common fungal agents of Otomycosis. Although Otomycosis rarely life-threatening, the disease is a challenging and frustrating entity for both patients and doctors as it requires long-term treatment and follow-up, despite this, there could be recurrences. Resistance in Aspergillus and Candida has been increasingly investigated and reported because of standards for susceptibility testing and associated breakpoints became available and as a consequence of the increased use of antifungal compounds. We aimed to determine the susseptibility of Amphotericin  B, Itraconazole, Voriconazole, and Clotrimazole on Aspergillusis strains isolated in Otomycosis patients referred toYasuj Shahid Mofatteh Clinic.

160 clinical species of Aspergillus spp, including 60 strains of A. flavus, 53 strains of A. Tubingensis, 43 strains of A. niger, 3 strains of A. terreus and 1 strain of A. fumigatus isolated from Otomycosis patient cultured on PDA medium and evaluated drug sensitivity of Amphotericin  B, Itraconazole, Voriconazole, and Clotrimazole according to the CLSI M38A2 guidelines

MIC50 and MIC90 of Amphotericin  B, Itraconazole, Voriconazole and Clotrimazole against A. flavus (1 and 2, 0.0156 and 0.0625, 0.125 and 0.25, 0.25 and 1), A. niger (2 and 4, 0.0625 and 0.25, 0.125 and 0.25, 0.5 and 1) and A. tubingensis (2 and 4, 0.125 and 0.5, 0.25 and 0.25, 1 and 1) were reported respectively. All strains of Aspergillus were sensitive to Itraconazole and Voriconazole.

The laboratory data obtained from this study showed that Itraconazole has the best antifungal effect against Aspergillus species, followed by Voriconazole, Clotrimazole and Amphotericin B, respectively. Itraconazole and Voriconazole appear to be alternative drugs for the treatment of Aspergillusis, but more studies are needed to investigate the resistance of different Aspergillus species to different antifungal drugs