In vitro susceptibility of filamentous fungi from mycotic keratitis to azole drugs

Objective. - The in vitro antifungal activities of azole drugs viz., itraconazole, voriconazole, ketoconazole, econazole and clotrimazole were investigated in order to evaluate their efficacy against filamentous fungi isolated from mycotic keratitis. Methods. - The specimen collection was carried out from fungal keratitis patients attending Aravind eye hospital and Post-graduate institute of ophthalmology, Coimbatore, India and was subsequently processed for the isolation of fungi. The dilutions of antifungal drugs were prepared in RPMI 1640 medium. Minimum inhibitory concentrations (MICs) were determined and MIC50 and MIC90 were calculated for each drug tested. Results. - A total of 60 fungal isolates were identified as Fusorium spp. (n = 30), non-sporulating moulds (n = 9), Aspergillus flavus (n = 6), Bipolaris spp. (n= 6), Exserohilum spp. (n = 4), Curvularia spp. (n = 3), Alternaria spp. (n = 1) and Exophiala spp. (n = 1). The MICs of ketoconazole, clotrimazole, voriconazole, econazole and itraconazole for all the fungal isolates ranged between 16 mu g/mL and 0.03 mu g/mL, 4 mu g/mLand 0.015 mu g/mL, 8 mu g/mL and 0.015 mu g/mL, 8 mu g/mL and 0.015 mu g/mL and 32 mu g/mL and 0.06 mu g/mL respectively. From the MIC50 and MIC90, values, it could be deciphered that in the present study, clotrimazole was more active against the test isolates at lower concentrations (0.12-5 mu g/mL) when compared to other drugs tested. Conclusion. - The results suggest that amongst the tested azole drugs, clotrimazole followed by voriconazole and econazole had lower MICs against moulds isolated from mycotic keratitis. (C) 2014 Elsevier Masson SAS. All rights reserved.