Susceptibility of clinical isolates of Candida lusitaniae to five systemic antifungal agents

Objectives: The aim of the present study was to expand the MIC database for Candida lusitaniae in order to further determine its antifungal susceptibility pattern. Methods: The activities of amphotericin B, fluconazole, itraconazole, voriconazole and flucytosine were determined in vitro against 80 clinical isolates of C. lusitaniae. A set of 59 clinical isolates of Candida albicans and of 51 isolates of Candida glabrata was included to compare the susceptibilities to amphotericin B. The MICs were determined by Etest with RPMI 1640 agar, and with both this medium and antibiotic medium 3 (AM3) agar for testing of amphotericin B. Results: All isolates were highly susceptible to fluconazole. The susceptibility to itraconazole was good; only 4% of isolates had dose-dependent susceptibility (MICs 0.25-0.5 mglL). Voriconazole was very active in vitro (100% of isolates were inhibited at ≤0.094 mglL). Flucytosine MICs ranged widely (0.004->32 mglL). The set included 19% of flucytosine-resistant isolates. For amphotericin B, 100% of isolates were inhibited at ≤0.75 mglL (MICA 0.047 mglL; MICA 0.19 mglL) and at ≤4 mglL (MICA 0.25 mglL; MICA 0.75 mglL) on RPMI and on AM3, respectively. A single isolate was categorized as resistant to amphotericin B (MIC 0.75 and 4 mglL on RPMI and on AM3, respectively). Amphotericin B thus appeared very active in vitro against C. lusitaniae. Whatever the test medium, the level of susceptibility of C. lusitaniae to amphotericin B did not differ much from those of C. albicans and C. glabrata. Conclusion: C. lusitaniae appears to be susceptible to amphotericin B, azole antifungal agents, and, to a lesser extent, flucytosine.