Based on morphological methods of identification, A. terreus is recognized as a single homogenous species within the section Terrei along with 2 other atypical variants, A. terreus var. africanus and A. terreus var. aureus. However, several recent studies have clearly shown that morphological characteristics may not be reliable markers for Aspergillus species identification and molecular methods could be powerful tools for delineating cryptic species within this genus. We recently developed a multi gene sequence approach employing three protein coding regions, Enolase [enoA], β tubulin [benA] and calmodulin [calM] [A. terreus sequencing project, Broad Institute of Harvard and MIT http://www.broad.mit.edu] to study species diversity in the section Terrei. After analyzing a large number of A. terreus isolates from clinical and environmental origins recovered from various parts of the world, we demonstrate the presence of a new, clinically relevant species Aspergillus alabamensis. Most members of this new species were recovered as colonizing isolates from immunocompetent populations and were morphologically similar to A. terreus with decreased in vitro susceptibilities to the antifungal drug amphotericin B. Further, based on phylogenetic and phenotype analyses, we also demonstrate that A. terreus var. africanus is a variant of A. terreus, whereas A. terreus var. aureus (considered as a morphological variant of A. terreus) should be raised to species within the section Terrei as Aspergillus aureus comb. nov. Results of this study also reveals that A. terreus is a truly cosmopolitan fungus with a global distribution since no population structure was revealed within the A. terreus clade.
Full conference title:
3rd Advances Against Aspergillosis
- AAA 3rd (2008)