Prospective Multicenter International Surveillance of Azole Resistance in Aspergillus fumigatus - Volume 21, Number 6—June 2015 - Emerging Infectious Disease journal - CDC
Volume 21, Number 6—June 2015
Prospective Multicenter International Surveillance of Azole Resistance in Aspergillus fumigatus
Azole resistance is increasingly recognized as a problem in aspergillus diseases (1). Within the Aspergillus fumigatus species complex, new sibling species have been reported to cause invasive aspergillosis; these species are generally intrinsically less susceptible than A. fumigatus sensu strictu to azole compounds (2). Acquired resistance to azoles in A. fumigatus has become a public health concern because of the presumed fungicide-driven route of resistance selection and the associated risk for geographic migration. Surveillance studies show that, in areas to which Aspergillus is endemic, the environmental route of resistance selection contributes to >90% of resistance mechanisms in azole-resistant aspergillus diseases (1,3). Azole resistance has been observed in patients with no recent history of azole therapy, and the mortality rate for patients with azole-resistant invasive aspergillosis was 88% (3).
Our objective was to investigate the prevalence of azole resistance in clinical Aspergillus isolates. A multicenter international surveillance network was established (Surveillance Collaboration on Aspergillus Resistance in Europe [SCARE-network]), comprising 22 centers from 19 countries (18 European and 4 non-European sites) (Figure 1). To detect azole-resistant A. fumigatus, we developed a phenotypic screening-method using a 4-well plate format with agar supplemented with itraconazole, voriconazole, and posaconazole (4). Each center was asked to screen for azole resistance for 12 consecutive months. For each screened isolate, patient characteristics were registered through an online questionnaire, and patients with invasive aspergillosis were classified according to the European Organization for the Research and Treatment of Cancer/Mycoses Study Group consensus definitions (5).
For every A. fumigatus isolate that grew on any of the azole-containing wells, the primary culture isolate was sent both to the Radboud University Medical Centre (Nijmegen, the Netherlands) and Statens Serum Institute (Copenhagen, Denmark) for molecular species identification, susceptibility testing according to the EUCAST (European Committee on Antimicrobial Susceptibility Testing) broth microdilution reference method (6), and determination of the full coding sequence of both strands of the cyp51A gene and the promoter region by PCR amplification. For every resistant isolate, a susceptible control isolate was assigned; this control isolate was the first susceptible isolate screened on the 4-well plate format in the same center after the resistant isolate, and they received molecular species identification and susceptibility testing according to the EUCAST broth microdilution reference method (6).
Dr. van der Linden is a medical doctor and researcher in the departments of Medical Microbiology and Pediatrics at the Radboud University Medical Centre Nijmegen, Nijmegen, the Netherlands. His research interests include invasive fungal diseases, especially the epidemiology of azole-resistantAspergillus diseases.
We thank Jan Zoll, Ton Rijs, Hein van der Lee, Diane Lamers-Jansen, and Birgit Brandt for excellent technical assistance. We also thank Monica Slavin, Orla Morrissey, and Alison Campbell for local site support.
This work was supported in part by an unrestricted research grant through the Investigator Initiated Studies Program (IISP) of Merck, Sharp & Dohme (MSD).
We declare that we have no conflicts of interest related to this study. J.L. received travel grants from Gilead and MSD and honorarium as a speaker from Pfizer. M.A. has received research grants, travel grants, and honorarium as a speaker or advisor from Astellas, Gilead, MSD, and Pfizer. A.W. received educational grants from Pfizer, Gilead, and MSD. K.L. received research grants from Gilead; Pfizer; and MSD and served on the speakers’ bureau of Pfizer and MSD. S.K. received research funds, travel grants, and honoraria as a speaker or advisor from Gilead, MSD, and Pfizer. E.D. received research grants, travel grants, and honorarium as a speaker or advisor from Astellas, Gilead, MSD, Bio-Rad, Ferrer International, Schering, and Innothera. P.G. received travel grants and honoraria as speaker from Astellas, Gilead, MSD, and Pfizer. J.B. served as a consultant for MSD, Pfizer, Astellas, and Mayne Pharma. C.M. received travel grants from Astellas, honorarium as a speaker from Pfizer, and grant support from Pfizer. C.K. received honoraria from Gilead, MSD, Pfizer, and Astellas. A.U. received a travel grant from Astellas and honoraria as a speaker from MSD and Pfizer. L.N. received travel grants from MSD and Pfizer. P.V. received research grants, has attended conferences, given lectures and participated in advisory boards or trials sponsored by various pharmaceutical companies.
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Suggested citation for this article: van der Linden JWM, Arendrup MC, Warris A, Lagrou K, Pelloux H, Hauser PM, et al. Prospective multicenter international surveillance of azole resistance in Aspergillus fumigatus. Emerg Infect Dis. 2015 Jun [date cited].http://dx.doi.org/10.3201/eid2106.140717