Necessity to identify the causative agent for appropriate treatment in fungal corneal ulcer: an in vitro study

Abstract

Fungal corneal ulcers are a major cause of preventable blindness. Different antifungal agents as natamycin, nystatin, fluconazole, itraconazole, voriconazole are used to treat these ulcers. Among these, natamycin is most widely used as a treatment modality. In natamycin non-responding cases, other drugs especially voriconazole is used. This study was done to assess the use of antifungal drugs in the treatment of fungal corneal ulcer by determining the minimum inhibitory concentration against common fungal pathogens. Minimum inhibitory concentration of fluconazole, itraconazole, voriconazole, nystatin and natamycin was assessed against the 61 isolated corneal fungal pathogens as per CLSI guidelines. MIC value of different antifungal agents varies as per fungal strains. Voriconazole showed the lowest MIC against the isolated fungi, in comparison to fluconazole and itraconazole. In comparison to other fungi, higher natamycin MIC was observed against Aspergillus species. Itraconazole is poorly effective against Fusarium sp. Identification of causative fungi is necessary before antifungal treatment. Lowest voriconazole MIC promotes its use as 1st line drug. Comparative higher natamycin MIC, especially against Aspergillus species, warns clinician to have MIC in each case of a non-responding fungal corneal ulcer.