In vitro fungicidal activities of voriconazole, itraconazole, and amphotericin B against opportunistic moniliaceous and dematiaceous fungi.
The NCCLS proposed standard M38-P describes standard parameters for testing the fungistatic antifungal activities (MICs) of established agents against filamentous fungi (molds); however, standard conditions are not available for testing their fungicidal activities (minimum fungicidal or lethal concentrations [MFCs]). This study evaluated the in vitro fungistatic and fungicidal activities of voriconazole, itraconazole, and amphotericin B against 260 common and emerging molds (174 Aspergillus sp. isolates [five species], 23 Fusarium sp. isolates [three species], 6 Paecilomyces lilacinus isolates, 6 Rhizopus arrhizus isolates, 23 Scedosporium sp. isolates, 23 dematiaceous fungi, and 5 Trichoderma longibrachiatum isolates). MICs were determined by following the NCCLS M38-P broth microdilution method. MFCs were the lowest drug dilutions that resulted in fewer than three colonies. Voriconazole showed similar or better fungicidal activity (MFC at which 90% of isolates tested are killed [MFC(90)], 1 to 2 microg/ml) than the reference agents for Aspergillus spp. with the exception of Aspergillus terreus (MFC(90) of voriconazole and amphotericin B, >8 microg/ml). The voriconazole geometric mean (G mean) MFC for Scedosporium apiospermum was lower (2.52 microg/ml) than those of the other two agents (5.75 to 7.5 microg/ml). In contrast, amphotericin B and itraconazole G mean MFCs for R. arrhizus were 2.1 to 2.2 microg/ml, but that for voriconazole was >8 microg/ml. Little or no fungicidal activity was shown for Fusarium spp. (2 to >8 microg/ml) and Scedosporium prolificans (>8 microg/ml) by the three agents, but voriconazole had some activity against P. lilacinus and T. longibrachiatum (G mean MFCs, 1.8 and 4 microg/ml, respectively). The fungicidal activity of the three agents was similar (G mean MFC, 1.83 to 2.36 microg/ml) for the dematiaceous fungi with the exception of the azole MFCs (>8 microg/ml) for some Bipolaris spicifera and Dactylaria constricta var. gallopava. These data extend and corroborate the available fungicidal results for the three agents. The role of the MFC as a predictor of clinical outcome needs to be established in clinical trials by following standardized testing conditions for determination of these in vitro values.
Espinel-Ingroff
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Division of Infectious Diseases, Medical Mycology Research Laboratory, Medical College of Virginia, Virginia Commonwealth University, P.O. Box 980049, Richmond, VA 23298-0049, USA. avingrof@hsc.vcu.edu
D000666:Amphotericin B / Q000494:pharmacology*; D000935:Antifungal Agents / Q000494:pharmacology*; D005658:Fungi / Q000187:drug effects*; D006801:Humans; D017964:Itraconazole / Q000494:pharmacology*; D008826:Microbial Sensitivity Tests / Q000379:methods / Q000592:standards; D009181:Mycoses / Q000382:microbiology; D009894:Opportunistic Infections / Q000382:microbiology; D011743:Pyrimidines / Q000494:pharmacology*; D014230:Triazoles / Q000494:pharmacology*; D065819:Voriconazole
D000935:Antifungal Agents; D011743:Pyrimidines; D014230:Triazoles; D017964:Itraconazole; D000666:Amphotericin B; D065819:Voriconazole