Correlation of posaconazole minimum fungicidal concentration and time kill test against nine Candida species.

OBJECTIVES

We evaluated the in vitro activity of posaconazole against nine Candida species using minimum fungicidal concentration (MFC) measurements and time-kill methods.

METHODS

MFCs of posaconazole were determined for 209 clinical isolates (32 Candida albicans, 30 Candida glabrata, 21 Candida tropicalis, 29 Candida krusei, 28 Candida parapsilosis sensu stricto, 50 Candida inconspicua, 13 Candida kefyr, 3 Candida lusitaniae and 3 Candida guilliermondii) and 7 ATCC Candida strains. The following strains were tested in time-kill studies: 3 strains each of C. glabrata, C. kefyr, C. guilliermondii and C. lusitaniae; 2 C. tropicalis; 4 C. albicans; 4 C. inconspicua; 9 C. krusei; 12 C. parapsilosis; and 7 ATCC strains.

RESULTS

Posaconazole was fungicidal in both MFC and time-kill experiments (at 2 mg/L within 48 h in time-kill assays) against each C. krusei, C. inconspicua and C. lusitaniae strain and was fungistatic against each C. albicans, C. glabrata, C. tropicalis and C. guilliermondii strain. For the C. parapsilosis strains, posaconazole MFCs were <or=2 mg/L for 20 of the 28 isolates tested; however, in the time-kill tests, even at drug concentrations of 32-64 x MIC, posaconazole was fungistatic against all C. parapsilosis strains tested.

CONCLUSIONS

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.