Aspergillus species identification in the clinical setting

Abstract

Multiple recent studies have demonstrated the limited utility of morphological methods used singly for species identification of clinically relevant aspergilli. It is being increasingly recognised that comparative sequence based methods used in conjunction with traditional phenotype based methods can offer better resolution of species within this genus. Recognising the growing role of molecular methods in species recognition, the recently convened international working group meeting entitled "Aspergillus Systematics in the Genomic Era" has proposed several recommendations that will be useful in such endeavors. Specific recommendations of this working group include the use of the ITS regions for inter section level identification and the beta-tubulin locus for identification of individual species within the various Aspergillus sections.

Keywords: Emericella; molecular phylogeny; pathogenic aspergilli; polyphasic taxonomy; section Aspergillus section Terrei; section Usti.

Fig. 1.

Phylogenetic tree of Aspergillus section Fumigati species inferred from Neighbour-Joining analysis of partial β-tubulin gene sequence. The shaded species have been reported from clinical environment.

Fig. 2.

Correlation among phylogeny, detailed morphology and maximal growth temperatures on Aspergillus section Fumigati. The letters L and M refer to the conidial ornamentation as observed by scanning electron microscopy.

Fig. 3.

Scanning electronmicroscopy of ascospores of Emericella species. A. E. nidulans. B. E. echinulata. C. E. quadrilineata. D. E. rugulosa. Scale bars = 5 μm.