[Studies on microtiter broth dilution method for antifungal susceptibility testing of yeast isolates from blood and cerebrospinal fluid].
Minimum inhibitory concentration (MICs) of amphotericin B (AMPH), fluconazole (FCZ), miconazole (MCZ), and flucytosine (5-FC) for five quality control (QC) strains, 135 Candida isolates from blood and 9 of Cryptococcus neoformans from the cerebrospinal fluid were determined by the microtiter broth dilution method. For FCZ, MCZ, and 5-FC, the MIC endpoints were defined at the concentrations of 50% (IC50), 80% (IC80), and 80% (IC80) growth inhibition in comparison with the growth control respectively. For AMPH, the MIC endpoint was at which concentration completely inhibited. The MICs were read after 24h incubation for C. albicans, C. tropicalis, C. glabrata and C. krusei, and 48h for C. guilliermondii, C. parapsilosis and C. neoformans. The MICs of four antifungal agents were determined 5 times each against the 5 QC strains, and the most MIC results ranged within the NCCLS QC range recommended. Four of 15 C. glabrata isolates (27%), four of 14 C. guilliermondii (29%) and three of 4 C. krusei (75%) were regarded to be resistant to FCZ (> or = 16 micrograms/mL), and one strain each of C. glabrata, C. guilliermondii and C. krusei were to MCZ (> or = 16 micrograms/mL). On the other hand, all the isolates tested were inhibited at the concentration of < or = 1 microgram/mL of AMPH. Overall, no significant increase in antifungal resistance among the yeast isolates during the period from 1980 to 1994 was noted.
Fujita
S
S
Department of Laboratory Medicine, Kanazawa University School of Medicine, Ishikawa, Japan.
D000666:Amphotericin B / Q000494:pharmacology; D000935:Antifungal Agents / Q000494:pharmacology*; D002175:Candida / Q000187:drug effects*; D003455:Cryptococcus neoformans / Q000187:drug effects*; D004352:Drug Resistance, Microbial; D015725:Fluconazole / Q000494:pharmacology; D005437:Flucytosine / Q000494:pharmacology; D008825:Miconazole / Q000494:pharmacology; D008826:Microbial Sensitivity Tests / Q000379:methods*
D000935:Antifungal Agents; D008825:Miconazole; D000666:Amphotericin B; D015725:Fluconazole; D005437:Flucytosine