This CLSI rationale document offers essential guidance on interpreting antifungal agents for treating invasive aspergillosis. It's a critical resource for health care professionals and researchers.

Aspergillosis, which is most commonly caused by Aspergillus fumigatus, is the most frequent invasive hyalohyphomycosis. Invasive aspergillosis is a devastating disease that occurs predominantly in immunocompromised individuals, particularly those with profound neutropenia. Voriconazole is one of the first triazoles developed that demonstrated significant activity against A. fumigatus in patients with invasive aspergillosis. However, A. fumigatus isolates with mutations in the CYP51 gene are known to produce elevated minimal inhibitory concentrations (MICs) to voriconazole and contribute to therapeutic failures. Therefore, antifungal susceptibility guidance is needed to alert clinicians to the likelihood of resistance, so that alternate therapeutic strategies can be considered.