Monitoring azole-resistance in clinical and environmental isolates of Aspergillus fumigatus in Germany

Ref ID: 19201

Author:

U. Groß*, D. Buchheidt, U. Reichard, M. Weig, O. Bader

Author address:

Göttingen, Mannheim, DE

Full conference title:

23rd European Congress of Clinical Microbiology and
Infectious Diseases

Date: 27 April 2014

Abstract:

Objectives: Azole-resistant Aspergillus fumigatus isolates carrying the TR/L98H mutation of the CYP51 gene are isolated with increasing frequency from the environment as well as from patients in several European and Asian countries.
Although being centrally located within Europe, a systematic monitoring of this emerging resistance pattern has not been performed in Germany, so far.
Methods: More than 300 randomly selected clinical isolates of A. fumigatus were collected within our nationwide network MycoLabNet-D. In addition, more than 400 soil samples from randomly selected geographic areas within entire Germany were tested. MALDI-TOF was used for Aspergillus species confirmation. Antifungal susceptibility testing against itraconazole (ITRA), posaconazole (POSA) and voriconazole (VORI) was done using the EUCAST broth microdilution method. Finally, DNA sequencing of the CYP51 gene of all ITRA-resistant isolates was performed and compared to non-resistant control strains.
Results: Out of the clinical A. fumigatus isolates, 15 (4.9%) showed azole resistance when tested against the lead substance ITRA. One of these was also resistant against POSA and an additional one showed decreased sensitivities against POSA and VORI. Sequencing of the CYP51 gene resulted in a high rate of variation ranging from (i) the TR/L98H mutation that seems to be associated with agricultural azole usage or other known mutations, (ii) novel mutations within the CYP51 gene to (iii) no mutation within the CYP51 gene. From 7.7% of the environmental samples analysed so far ITRA-resistant isolates could be obtained. However, a geographic hot spot for azole resistance could neither be identified for the clinical nor for the environmental samples.
Conclusion: Azole-resistant A. fumigatus isolates were identified at a ratio of 4.9-7.7% in Germany. Although azole resistance is mainly restricted to ITRA, so far, a foresighful management of patients with aspergillosis is important to control the spread of this emerging resistance threat.
Supported by grants from the BMG and PFIZER.

Abstract Number: P994

Conference Year: 2013

Link to conference website: http://registration.akm.ch/einsicht.php?XNABSTRACT_ID=160381&XNSPRACHE_ID=2&XNKONGRESS_ID=180&XNMASK

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