Molecular characterization and identification of Aspergillus isolates collected in Saint Petersburg, Russia

Ref ID: 19427

Author:

Y. V. Mikhaylova, G. A. Chilina, D. M. Lavnikevich,
T. S. Bogomolova and A. G. Polischouk

Author address:

North-Western State Medical University named after I.I.
Mechnikov, Saint Petersburg, Russian Federation

Full conference title:

6th Trends in Medical Mycology 2013

Date: 11 October 2014

Abstract:

Objectives Aspergillus species are associated with a variety of inva-
sive and cutaneous infection diseases, from which infections of the
bronchopulmonary system, ear canals and sinuses are the most com-
mon forms. Species identification of Aspergillus may be important due
to differences in antifungal drug susceptibility. Phenotype-based iden-
tification of Aspergillus allows recognizing isolates to species complex
level. DNA sequence-based identification can demarcate species
within the complexes and reveal cryptic species, that are not possible
to identify using classical methods and frequency of which is not
known at present time.
The objectives of this study was to characterize spectrum of Asper-
gillus species in clinical isolates collected in Saint Petersburg area
(Russia) using morphological criteria and sequence analysis of frag-
ments of rDNA and b-tubulin genes.
Methods Seventy one Aspergillus isolates were obtained from the Rus-
sian Collection of Pathogenic Fungi at Kashkin Research Institute of
Medical Mycology in Saint Petersburg (Russia). 50 isolates were from
different clinical specimens. 21 isolates were obtained from All Russian
Collection of Microorganisms in Moscow (VKM) and Komarov Botani-
cal Institute in Saint Petersburg. Isolates were identified both morpho-
logically and by two-loci sequencing (ITS1-5.8S-ITS2 and b-tubulin).
Sequences were compared with GenBank database. The identification
to species level was concluded at 99-100% sequence identity. Phylo-
genetic analysis was done by MEGA 5.03 software.
Results Morphological analysis identified 68 isolates to species com-
plex level and three isolates to genus level. 46 (64%) isolates were
unambiguously identified to species level by ITS sequencing (all were
A. fumigatus and A. terreus isolates), whereas 65 (92%) isolates were
unambiguously identified to species level by b-tubulin sequencing.
Sixth (8%) ambiguously identified isolates belonged to A. niger and A.
versicolor species complexes. For precise species identification of these
isolates phylogenetic analysis of their b-tubulin sequences and b-
tubulin sequences of the type strains available in GenBank was per-
formed. Two ambiguous “œversicolor”isolates grouped together with
A. jensenii on the neijbour-joining tree. Phylogenetic analysis of
“œniger”group revealed four isolates with an intermediate genotype
between A. awamorii and A. niger.
Thirty isolates were obtained from patients with invasive aspergil-
losis of lung. The species associated with this disease were A. fumiga-
tus (n = 14), A. flavus (n = 5), A. tubingensis (n = 3), niger (n = 3),
A. sydowii (n = 2), A. terreus (n = 1), A. amstelodami (n = 1) and A.
calidoustus (n = 1). Then isolates were obtained from patients with
otomycosis. The species associated with this disease were A. niger
(n = 3), A. awamori (n = 3), A. flavus (n = 2), A.terreus (n = 1) and
A. sydowii (n = 1). Three isolates were obtained from patients with
fungal sinusitis. The species associated with it were A. flavus (n = 2)
and A.sclerotiorum (n = 1).
Conclusion In most cases, b-tubulin locus sequencing can ade-
quately discriminate Aspergillus species, including cryptic species. We
have revealed four isolates that genetically correspond to an interme-
diate species form between A. awamorii and A. niger. The most com-
mon species associated with invasive aspergillosis of lung was A.
fumigatus, whereas with otomycosis – A. niger and A.awamori, with
nasal aspergillosis – A. flavus.

Abstract Number: p228

Conference Year: 2013

Link to conference website: NULL

New link: NULL

Conference abstracts, posters & presentations

Showing 10 posts of 17325 posts found.

  • Title

    Author

    Year

    Number

    Poster