No abstract

In vitro activity of caspofungin against C. dubliniensis depended on the starting inoculum and medium used. Using AM3 eliminated trailing from MIC determinations but not PG in MIC, MFC and time-kill tests.

MFC values were good predictors of the fungistatic or fungicidal activity of posaconazole, as determined by time-kill curves, for all tested species except C. parapsilosis. Our results highlight the fungicidal action of posaconazole against a number of clinically relevant Candida species.

Paradoxical growth was noted in RPMI 1640 and antibiotic medium 3 in the case of 14 and 1 of 15 Candida tropicalis strains, respectively, at a caspofungin concentration of 12.5 g/ml using minimum fungicidal concentration tests. Time-kill assays showed that against isolates killed at lower concentrations, caspofungin at a concentration of 12.5 g/ml was only fungistatic.

Candida inconspicua is an emerging pathogen in immunocompromised patients possessing inherently decreased susceptibility to fluconazole. We determined the MICs and killing activity of fluconazole and amphotericin B against C. inconspicua clinical isolates as well as reference strain C. inconspicua ATCC 16783 for comparison. MICs were determined using the standard broth microdilution method. Killing rates were determined using time-kill methodology at 0.5-16 x MIC fluconazole and amphotericin B concentrations. Fluconazole and amphotericin B MIC values varied between 16-128 mg/l and 0.5-1 mg/l, respectively. In time kill-assays fluconazole showed fungistatic effect at 1-16 x MIC concentrations against all tested strains after 24 h-incubation, but became fungicidal after 48 h at 4-16 x MIC concentrations. The time necessary to achieve fungicidal endpoint at 1 mg/l amphotericin B concentration ranged from 2 to 24 h. Our in vitro results confirm the data that fluconazole is ineffective against C. inconspicua at the fluconazole serum concentration attainable in humans. Amphotericin B due to its rapid killing activity seems to be a good alternative for the treatment of infections caused by C. inconspicua.