Caspofungin-Non-Susceptible Candida orthopsilosis Isolated from Onychomycosis in Iran

BACKGROUND: Although Candida albicans remains the most common fungal isolate from clinical specimens, many studies have detected a shift towards non-albicans Candida species. Despite worrying clinical pictures associated with latter species, there is little information regarding its susceptibility patterns against currently available antifungal agents, with only a small number of strains having been studied. METHODS: We evaluated the in vitro antifungal susceptibilities of clinical isolates of C. orthopsilosis already identified by two-steps PCR-RFLP and reconfirmed by sequence analysis of entire ITS rDNA region, to six antifungal drugs. RESULTS: The resulting MIC(50) and MIC(90) for all strains (n=18) were in increasing order, as follows: posaconazole (0.016 & 0.063 μg/ml); itraconazole (0.031 & 0.125 μg/ml); amphotericin B (0.5 & 1 μg/ml); fluconazole (0.25 & 0.5 μg/ml) and caspofungin (4 & 8 μg/ml). A uniform pattern of the MIC ranges was seen for amphotericin B, fluconazole, itraconazole, and posaconazole, while a widest range and the highest MICs were observed for caspofungin. CONCLUSION: Although we emphasis on the careful species designation of the clinical isolates of Candida, the antifungal susceptibility patterns of these clinically important organisms may have an application in clinical and epidemiological setting and deserve the implementation of local surveillance programs to monitor.