The objective of this study was to compare the susceptibility pattern of clinical and environmental isolates of Aspergillus to antifungal agents such as, amphotericin B (AMB), itraconazole (ITC), voriconazole (VRC) and caspofungin (CPF). Seventy-four clinical and 188 environmental strains of A. fumigatus (47 vs 72), A. flavus (20 vs 47), A. niger (2 vs 34), A. terreus (2 vs 5), A. nidulans (2 vs 2) and A. glaucus (1 vs 28) were used. The determination of the minimal inhibitory concentration (MIC) of the antifungal agents AMB, ITC and VRC was performed accordingly NCCLS M38-A protocol for susceptibility testing of moulds. The reduction of 90% of growth defined the MIC. CPF activity was also determined accordingly NCCLS M38-A protocol being evaluated the minimal effective concentration (MEC). No significant differences were found comparing the susceptibility profiles of clinical and environmental strains of Aspergillus. No resistant strains were found in this study (MIC>8 μg/ml). A high MIC value to AMB (4 μg/ml) was found with 1 clinical strain of A. flavus and 1 environmental strain of A. terreus. The highest MIC value to ITC found was 4 μg/ml in 1 clinical and 1 environmental strain, both of A. flavus. MIC values to AMB in the case of A. flavus were higher comparing with other Aspergillus species. MIC of VRC and MEC of CPF were invariably below 2 μg/ml, in all tested strains. A. glaucus presented significantly lower MIC and MEC comparing with the other species. The susceptibility pattern of clinical versus environmental strains of Aspergillus was similar. Resistance is uncommon both among clinical and environmental isolates. The susceptibility pattern of A. fumigatus does not justify the enhanced pathogenic potential comparing with other Aspergillus species.
Full conference title:
15th Annual Focus on Fungal Infections
- FFI 15th (2005)