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Journal of Clinical Microbiology, April 2000, p. 1510-1515, Vol. 38, No. 4
Department of Pathology and Microbiology,
University of Nebraska Medical Center, Omaha, Nebraska
Received 8 July 1999/Returned for modification 29 November
1999/Accepted 25 January 2000
Aspergillus species are the most frequent cause of
invasive mold infections in immunocompromised patients. Although over
180 species are found within the genus, 3 species, Aspergillus
flavus, A. fumigatus, and A. terreus,
account for most cases of invasive aspergillosis (IA), with A. nidulans, A. niger, and A. ustus being rare causes of IA. The ability to distinguish between the various clinically relevant Aspergillus species may have diagnostic
value, as certain species are associated with higher mortality and
increased virulence and vary in their resistance to antifungal therapy. A method to identify Aspergillus at the species level and
differentiate it from other true pathogenic and opportunistic molds was
developed using the 18S and 28S rRNA genes for primer binding sites.
The contiguous internal transcribed spacer (ITS) region, ITS
1-5.8S-ITS 2, from referenced strains and clinical isolates of
aspergilli and other fungi were amplified, sequenced, and compared with
non-reference strain sequences in GenBank. ITS amplicons from
Aspergillus species ranged in size from 565 to 613 bp.
Comparison of reference strains and GenBank sequences demonstrated that
both ITS 1 and ITS 2 regions were needed for accurate identification of
Aspergillus at the species level. Intraspecies variation
among clinical isolates and reference strains was minimal. Sixteen
other pathogenic molds demonstrated less than 89% similarity with
Aspergillus ITS 1 and 2 sequences. A blind study of 11 clinical isolates was performed, and each was correctly identified.
Clinical application of this approach may allow for earlier diagnosis
and selection of effective antifungal agents for patients with IA.
0095-1137/00/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.
Identification of Aspergillus Species
Using Internal Transcribed Spacer Regions 1 and 2
*
Corresponding author. Mailing address: Department of
Pathology and Microbiology, University of Nebraska Medical Center,
986495 Nebraska Medical Center, Omaha, NE 68198-6495. Phone: (402)
559-4040. Fax: (402) 559-4077. E-mail: piwen{at}unmc.edu.
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