In vitro susceptibility of dematiaceous fungi to nine antifungal agents determined by two different methods

Abstract

The infection rate for dematiaceous fungi has increased rapidly over the most recent decades. However, the treatment for such infections has been lacking in empirical support with oral antifungal agents. To provide a better regimen for dematiaceous infections in future, the Sensititre YeastOne® colorimetric antifungal panels were used and compared with Laboratory Standards Institute (CLSI) M38-A2 reference broth microdilution method. Two methods were used for nine antifungals against 67 dematiaceous fungi. Via two methods, we found that the MICs of itraconazole, voriconazole, posaconazole and amphotericin B were lower than fluconazole. The values obtained with CLSI method for four triazoles, 5-flucytosine and amphotericin B were in high essential agreements with those observed by YeastOne® method. The results of echinocandins across the two methods showed some divergence, which might be attributed to the methodology itself, particularly when sensitivity was determined in the lowest concentration of the drug. In YeastOne® method, the results were defined as MICs, but as MECs in CLSI method. The YeastOne®method appeared to be both easier and more efficient for dematiaceous fungi when compared with the CLSI method, and the agreement between the two methods was good for most common antifungals.