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United States Department of Agriculture

Agricultural Research Service

Research Project: Genomic Analyses and Management of Agricultural and Industrial Microbial Genetic Resources and Associated Information

Location: Bacterial Foodborne Pathogens & Mycology Research Unit

Title: Aspergillus pragensis sp. nov. discovered during molecular reidentification of clinical isolates belonging Aspergillus section Candidi

Authors
item Hubka, Vit -
item Lyskova, Pavlina -
item Frisvad, Jens -
item Skorepova, Magdalena -
item Peterson, Stephen
item Kolarik, Miroslav -
item Skorepova, Magdalena -

Submitted to: Medical Mycology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 3, 2014
Publication Date: July 18, 2014
Citation: Hubka, V., Lyskova, P., Frisvad, J.C., Skorepova, M., Peterson, S.W., Skorepova, M., Kolarik, M. 2014. Aspergillus pragensis sp. nov. discovered during molecular reidentification of clinical isolates belonging Aspergillus section Candidi. Medical Mycology. 52(6):565-576.

Interpretive Summary: Molds in the toxin forming and food decaying groups called Talaromyces and Biverticillium have long thought to be distinct groups because while they resemble each other, one reproduces sexually and the other group is strictly asexual. Recent advances in DNA sequencing technology and mold genetics show that the two groups should be treated as a single group, some of which have sex in a way that is not observed. We used DNA sequences to analyze the natural relationships of the species and changed names to reflect the true genetic relations of the species. This will make it simpler to understand study results and will also lead to long-term stability of mold names based on natural relationships.

Technical Abstract: The identity of nine clinical isolates from Czech patients presumably belonging to Aspergillus section Candidi based on morphology of colonies was revised using sequences of ß-tubulin, calmodulin, and internal transcribed spacer (ITS) rDNA. The set of isolates included six isolates from suspected (not verified using standard criteria) and proven onychomycosis, one isolate from otitis externa, and two isolates associated with probable invasive aspergillosis. The results showed that A. candidus isolate was a cause of otitis externa, both isolates from sputum of patients with probable invasive aspergillosis (IA) were excluded from section Candidi and re-identified as A. carneus (sect. Terrei) and A. flavus (sect. Flavi). The isolates from nail scrapings were mostly identified as A. tritici (n=3), a verified agent of non-dermatophyte onychomycosis. One isolate from toenail was identified as A. candidus and two isolates belonged to a hitherto undescribed species. This species is well supported by phylogenetic analysis based on ß-tubulin and calmodulin gene. This species is distinguished from all other members of section Candidi by white colonies on malt extract agar (MEA) with red-brown reverse, very slow growth on Czapek-Dox agar and inability to grow at 37 °C. We propose for this species the name A. pragensis related to the locality of isolation. Section Candidi encompasses five species (including A. pragensis sp. nov.) for which a dichotomous key based on colonies characteristics is provided. All seven clinical isolates from sect. Candidi were tested for susceptibilities to selected antifungal agents using Etest and disc diffusion method. Our results indicate that sect. Candidi species have overall good susceptibility to common antifungals.

Last Modified: 10/24/2014
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