Comparison of the Etest and microdilution method for antifungal susceptibility testing of Cryptococcus neoformans to four antifungal agents.
We performed a prospective study to compare the Etest and the microdilution method (NCCLS guidelines) for determining the MICs of fluconazole, itraconazole, flucytosine and amphotericin B for 35 strains of Cryptococcus neoformans. For the microdilution method (MDM) RPMI 1640 medium with 2% glucose was used for fluconazole, itraconazole and flucytosine, and Antibiotic Medium 3 for amphotericin B. For the Etest, RPMI 1640 medium with 2% glucose and solidified with 1.5% agar was used for the four antifungal agents. Amphotericin B was also tested on Antibiotic Medium 3 solidified with 1.5% agar. Fluconazole and flucytosine MICs by the Etest showed good correlation with the broth MDM (81.1 and 89.2% agreement within two dilutions, respectively). With the tested population of itraconazole- and amphotericin B-susceptible isolates, the MIC agreement for itraconazole was 54%; amphotericin B showed the lowest agreement (8.1% on Antibiotic Medium 3 and 13.5% on RPMI).
Aller
A I
AI
Servicio de Microbiología, Hospital Universitario de Valme, Carretera de Cádiz s/n, E-41014 Seville, Spain.
Martín-Mazuelos
E
E
Gutiérrez
M J
MJ
Bernal
S
S
Chávez
M
M
Recio
F J
FJ
D000666:Amphotericin B / Q000494:pharmacology; D000935:Antifungal Agents / Q000494:pharmacology*; D003455:Cryptococcus neoformans / Q000187:drug effects*; D015725:Fluconazole / Q000494:pharmacology; D005437:Flucytosine / Q000494:pharmacology; D017964:Itraconazole / Q000494:pharmacology; D008826:Microbial Sensitivity Tests / Q000379:methods*; D012189:Retrospective Studies
D000935:Antifungal Agents; D017964:Itraconazole; D000666:Amphotericin B; D015725:Fluconazole; D005437:Flucytosine