Ocular Fungi: Molecular Identification and Antifungal Susceptibility Pattern to Azoles

 Treatment of ocular infection by fungi has become a problematic issue, particularly in deep lesion cases, because of the limited available antifungals and emerging resistance species.

 The present study was designed for molecular identification and studying the antifungal susceptibility pattern of ocular fungi.

 Fifty-three ocular fungal isolates, including Fusarium spp., Aspergillus spp., yeast spp., and dematiaceous fungi were collected. Initial identification of each sample was performed using routine mycological techniques. ITS1-5.8SrDNA-ITS2 and translation elongation factor (TEF)-1α regions were used for the identification and differentiation of ocular non-Fusarium and Fusarium fungal species, respectively. The antifungal susceptibility of itraconazole, voriconazole, and posaconazole was determined according to the CLSI guidelines (CLSI M38 and M60, 3rd ed.) for filamentous and yeast species, respectively.

 Voriconazole and posaconazole showed excellent activity in all tested isolates; however, some of Fusarium, Aspergillus, and Curvularia strains showed minimum inhibitory concentration (MIC) ≥ 2 μg/mL. The itraconazole showed different results in all species, and high MICs (≥ 16 μg/mL) were found.

 Finally, in the present study, we tried to identify species involved in fungal ocular infection using the molecular methods, which highlighted the importance of precise identification of species to choose an appropriate antifungal regime. On the other hand, our findings showed that antifungal susceptibility test is effective to reliably predict the in vivo response to therapy in infections; however, in fungal ocular infection cases, the penetration of antifungals may contribute to predict the outcome.