Azole antifungal resistance in Aspergillus fumigatus complex: 2010 and 2011

Ref ID: 19175

Author:

C.B. Moore, A. Bueid, P. Bowyer, R. Rautemaa, D.W. Denning*, M.D. Richardson

Author address:

Manchester, GB

Full conference title:

23rd European Congress of Clinical Microbiology and
Infectious Diseases

Date: 27 April 2014

Abstract:

Objectives: Resistance to triazole antifungal agents in Aspergillus fumigatus has been increasing in frequency in recent years, primarily in patients with chronic forms of pulmonary aspergillosis. In the Mycology Reference Centre Manchester, 14% and 20% of patients had resistant isolates in 2008 and 2009, respectively. During this period, 97% of isolates were itraconazole resistant, 3% were only voriconazole resistant and 78% of cases were multi-azole resistant. Here we update our previous experience with data from 2010-11.
Methods: We tested all A. fumigatus complex isolates submitted to our centre in 2010 and 2011 for susceptibility to itraconazole, voriconazole and posaconazole, using a modified EUCAST method (final inoculum of 0.5×10^5 CFU/mL). The breakpoint used for resistance was >=4 mg/L for itraconazole and voriconazole, and >=1.0 mg/L for posaconazole.
Results: Of 394 isolates (from 295 patients), 52 isolates (13%) were resistant to at least one azole. Chronic pulmonary aspergillosis was the most common underlying condition (80% of patients). Itraconazole, voriconazole and posaconazole resistance was seen in 87%, 52% and 57% of isolates, respectively. Multi-azole resistance was seen in 29% of isolates. In 2010 and 2011, 12% (n=19) and 15% (n=21) of patient cases had resistant isolates, resp. (graph). Of the 40 patients harbouring a resistant isolate, 93%, 50% and 58% were resistant to itraconazole, voriconazole and posaconazole, resp. Pan-azole resistance was reported in twelve cases (30%), of which 8 were new cases since 2010. Interestingly, cross-resistance between itraconazole and voriconazole, but not posaconazole was observed.
Conclusion: Azole resistance remains of major clinical concern, especially during long-term therapy of chronic aspergillosis patients.

Abstract Number: P989

Conference Year: 2013

Link to conference website: http://registration.akm.ch/einsicht.php?XNABSTRACT_ID=166146&XNSPRACHE_ID=2&XNKONGRESS_ID=180&XNMASK

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