RODRIGUEZ-TUDELA JL, MARTIN-DIEZ F, CUENCA-ESTRELLA M, RODERO L, CARPINTERO Y, GORGOJO B; Interscience Conference on Antimicrobial Agents and Chemotherapy.
Abstr Intersci Conf Antimicrob Agents Chemother Intersci Conf Antimicrob Agents Chemother. 1999 Sep 26-29; 39: 546 (abstract no. 161).
Inst. de Salud Carlos III, Majadahonda, SPAIN
CN is non-fermentative yeast that requires oxygen for its growth. The shaking of culture media achieves a good oxygenation promoting the growth of CN. This study was designed to compare the following methodologies: NCCLS M27A, YNB pH 7.0, RPMI2% glucose and Antibiotic Medium 3 (AM3) with and without agitation of the microplates. Thirty-three CN were used for antifungal susceptibility testing and 21 of them were obtained from patients with known response to amphotericin B. In addition, spectrophotometric growth curves were performed for 16 isolates. The following antifungals and their ranges were used amphotericin B (8-0.015 microg/ml), flucytosine and fluconazole (64-0.12 microg/ml) and itraconazole (4-0.007 microg/ml). All methodologies were done following strictly the published procedures. QC strains recommended by NCCLS were used throughout all experiments. The growth curves demonstrated: 1. Shaking is necessary to obtain an adequate growth curve pattern (lag, logarithmic and stationary) 2. A 2% concentration of glucose did not add any advantage to CN growth. 3. The size of the inoculum is very important for a proper growth of CN. All comparisons between shaking vs static cultures were statistically significant (p<0.05 Student t test). The MICs obtained with static procedure were discarded because of the poor growth. The MICs obtained after shaking were difficult to interpret because of the limited growth in NCCLS M27-A. In RPMI 2% glucose all isolates grew well but it seems that the size of inoculum is more important than glucose supplementation. For flucytosine and fluconazole the widest range was obtained with YNB pH 7.0 With AM3 higher MICs tend to be obtained with those isolates from patients with poor response to amphotericin B. The results of this study suggests the need of a new methodology for CN antifungal susceptibility testing.
Publication Types:
Keywords:
- Amphotericin B
- Antifungal Agents
- Antigens, Fungal
- Cryptococcosis
- Cryptococcus neoformans
- Culture Media
- Fluconazole
- Flucytosine
- Humans
- Itraconazole
- Miconazole
- Microbial Sensitivity Tests
- Psychomotor Agitation
- Research Design
- immunology
- methods
Other ID:
UI: 102246878
From Meeting Abstracts