Screening of cryptic species among clinical Aspergillus isolates collected during one year period in a Portuguese reference laboratory

Ref ID: 19425

Author:

R. Sabino,1 C. M. Ver 305;ssimo,1 H. L. Parada,1 C. V. Clemons2 and D. A. Stevens2

Author address:

1Nacional Institute of Health Dr. Ricardo Jorge, Portugal and
2California Inst Med Research/Sta Clara Valley Med Center/
Stanford University, San Jose, USA

Full conference title:

6th Trends in Medical Mycology 2013

Date: 11 October 2014

Abstract:

Objectives Correct identification of Aspergillus species is important
given that sibling species may show variable susceptibilities to multi-
ple antifungal drugs and also because sharper definition of species
may facilitate epidemiological studies. Thus, we screened Aspergillus
clinical isolates from Portuguese hospitals to determine which, if any,
of the cryptic species of Aspergillus were involved in patient
infections.
Methods Over a one year period, Aspergillus isolates from Portu-
guese health institutions were collected. These isolates were identified
on the basis of microscopic morphology and through the use of
molecular tools. Genomic DNA was prepared from each isolate and
the sequencing of the Internal Transcribed Spacers (ITS) regions, spe-
cifically the ITS1 and ITS2 non-coding regions flanking the 5.8S
rDNA was used to determine the species complex, whereas b-tubulin and calmodulin sequencing was done to achieve the correct species
identification.
Results Over the study period, 57 Aspergillus isolates from clinical
samples were collected from 10 Portuguese health institutions.
According to the morphological observations, 29 isolates were identi-
fied as Aspergillus fumigatus, 11 A. flavus, 8 A. niger, 3 A. nidulans, 2
A. terreus, 2 A. candidus and 2 Aspergillus sp. Among those isolates,
six species-complexes were detected by ITS sequencing, and were dis-
tributed as follows: fumigati (50.1%), flavi (21.0%), nigri (15.8%), ter-
rei (5.3%), nidulantes (3.6%) and versicolores (3.6%). b-tubulin and
calmodulin sequencing resulted in ten (17.5%) cryptic species being
identified among the 57 isolates. Six of those isolates belonged to the
nigri complex (A. brasiliensis, A. awamorii and A. tubigensis), two to
the versicolores complex (A. sidowii and A. fructus), one to the fumigati
complex (A. lentulus) and one to the nidulantes complex (Emmericella
echinulata).
Conclusion With rigorous application of molecular tools, cryptic
species of Aspergillus are not uncommon in the clinic. The identifica-
tion of cryptic species among the collected clinical isolates of Aspergil-
lus alerts the clinician to isolates with reduced susceptibilities to
antifungal drugs and emphasizes a correct identification to species
level.

Abstract Number: p222

Conference Year: 2013

Link to conference website: NULL

New link: NULL


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