agar and posaconazole

Triazole prophylaxis has become the norm in patients with hematological malignancies. Breakthrough infections caused by Mucorales during triazole prophylaxis remain a challenging problem. We found that preexposure of Rhizopus oryzae to antifungal triazoles (fluconazole, voriconazole, posaconazole, and itraconazole) did not modify the in vitro susceptibility of Rhizopus oryzae to posaconazole. In contrast, preexposure of Rhizopus to triazoles was associated with the enhanced in vitro susceptibility of R. oryzae to amphotericin B. Preexposure to posaconazole did not alter the virulence of R. oryzae in the fly model of mucormycosis.

Topics: Agar; Animals; Antifungal Agents; Culture Media; Disease Models, Animal; Drosophila melanogaster; Female; Fluconazole; Itraconazole; Microbial Sensitivity Tests; Mucormycosis; Rhizopus; Survival Analysis; Triazoles; Virulence; Voriconazole

A multilaboratory collaborative study was performed in order to propose quality control limits for posaconazole disk diffusion susceptibility tests on Mueller-Hinton agar supplemented with 2% glucose and 0.5 microg of methylene blue per ml. Replicate tests were performed on three lots of prepared media using 5-microg posaconazole disks in each of eight laboratories to generate data to propose quality control zone diameter ranges for tests of Candida albicans ATCC 90028 (24 to 34 mm), C. parapsilosis ATCC 22019 (25 to 36 mm), C. tropicalis ATCC 750 (23 to 33 mm), and C. krusei ATCC 6258 (23 to 31 mm).

Topics: Agar; Antifungal Agents; Candida; Candida albicans; Candida tropicalis; Culture Media; Glucose; Methylene Blue; Microbial Sensitivity Tests; Quality Control; Triazoles

We performed Etest, disk diffusion, and broth microdilution susceptibility testing of 2,171 clinical isolates of Candida spp. against posaconazole. By using provisional breakpoints for comparison purposes only, the categorical agreement between the agar-based methods and broth microdilution results ranged from 93 to 98%, with <1% very major errors. The essential agreement (within 2 well dilutions) between the Etest and broth microdilution methods was 94%. These agar-based methods hold promise as simple and reliable methods for determination of the posaconzole susceptibilities of Candida spp.

Topics: Agar; Antifungal Agents; Candida; Candidiasis; Culture Media; Disk Diffusion Antimicrobial Tests; Humans; Microbial Sensitivity Tests; Triazoles

We compared two methods for the preservation of fungi, Castellani's method and repeated passage in Sabouraud medium-agar, on five isolates of Sporothrix schenckii that were preserved for 18 years at room temperature by both procedures. They were evaluated for viability of the strains, growth rate, morphological and physiological characteristics, and in vitro sensitivity to iodide, itraconazole, terbinafine and posaconazole. 100% viability was observed in all of the isolates, with slower growth rate on strains preserved in water compared to strains periodically re-cultured. The typical morphological feature of these fungi was preserved by both methodologies. With regard to enzymatic activity, both groups gave urease reactions and were beta glucosidase-positive. Nevertheless, complete inhibition of the capacity to hydrolyse starch was observed only on the isolates preserved in water. This group also was more sensitive to potassium iodide at a concentration of 10 microM in the in vitro sensitivity tests.

Topics: Agar; Antifungal Agents; Drug Resistance, Fungal; Glucose; Itraconazole; Microbial Sensitivity Tests; Mycology; Naphthalenes; Potassium Iodide; Preservation, Biological; Sporothrix; Starch; Terbinafine; Time Factors; Triazoles; Water