Purpose: To investigate the causative fungi of fungal keratitis in Japan and their drug susceptibility.
Methods: Identification and antifungal susceptibility test for 8 drugs (micafungin, amphotericin B, flucytosine, fluconazole, itraconazole, voriconazole, miconazole and pimaricin) were performed using isolated fungi from patients with fungal keratitis treated at 27 facilities in Japan between November 1, 2011 and October 31, 2013.
Results: Fungal strains were detected in 72 (50.7%) out of 142 samples. The major isolates were Fusarium spp. (18), Candida parapsilosis (12), C. albicans (11) and Alternaria spp. (6), in all, fungi of 31 species were identified by gene analysis. In the yeast-like fungi, susceptibility rates were evident for more than 80% in voriconazole, pimaricin, flucytosine, micafungin, amphotericin B and fluconazole. In filamentous fungi, the susceptibility rate was less than 50% except for PMR (90%). Fusarium spp., which were susceptible to amphotericin B and pimaricin, showed lower susceptibility rates compared with other genera.
Conclusions: Although various genera and species of fungi cause fungal keratitis, the obtained drug susceptibility data in this study demonstrates the different susceptibility patterns among the major isolates (Fusarium spp., C. parapsilosis, C. albicans and other groups). This is important evidence useful for fungal keratitis treatment.