Evaluation of different in vitro procedures for testing amphotericin B anditraconazole susceptibility of Aspergillus fumigatus - Antifungal susceptibility testing of Aspergillus fumigatus

Objective. The aim of the study was to analyze the influence of different p arameters of in vitro antifungal susceptibility testing of Aspergillus fumi gatus strains on the inter- and intra-laboratory reproducibility and on the ability to detect itraconazole resistance. Methods. Amphotericin B and itraconazole testings were performed in paralle l by two laboratories with the broth microdilution and agar dilution method , combining different test conditions. Results and conclusions. No differences were observed comparing media (RPMI 1640 and Antibiotic medium 3), types of inoculum (conidia alone and hyphae mixed with conidia), incubation times (48 and 72 h), and solvents for diss olving itraconazole. Broth microdilution with optical endpoint determinatio n showed a higher interlaboratory agreement and was more effective in detec ting itraconazole resistance of in vivo proven resistant strains.