Lass-Flörl C. Future Microbiol 2010;5:789–99.
The present article is a review of in vitro susceptibility testing in Aspergillus spp. Different methods of susceptibility testing are discussed, including macro- and microdilution, disk-based diffusion, Etest, and other commercial tests. In addition, the clinical implications of in vitro testing are discussed, taking into account intrinsic resistance and the recent emergence of azole resistance among Aspergillus spp. against a range of antifungal compounds.
Aspergillus spp. are known to cause a wide range of clinical symptoms, mostly in immunocompromised patients. Aspergillus fumigatus is the most frequent species isolated from clinical specimens, followed by Aspergillus niger, Aspergillus flavus, and Aspergillus terreus [1]. Although Aspergillus spp. are generally susceptible to various antifungal compounds such as amphotericin B formulations, azoles, and candins, intrinsic and acquired resistance has been documented. Host status, delay in diagnosis, lack of efficient antifungal therapy, and infection with a drug-resistant fungal pathogen are all important factors associated with a poor outcome of invasive aspergillosis (IA). Antifungal susceptibility testing allows early insight into drug activity and enables proactive patient management. However, clinically derived breakpoints are not currently available for Aspergillus spp. Thus, the present authors discuss the available methods of in vitro susceptibility testing in Aspergillus spp. and the clinical relevance of such tests.