M-1718. Prospective Study of the Prevalence of Azole Resistance in Aspergillus Species in the Netherlands
Session: Slide Session: From the Clinical Mycology Laboratory
Sunday, October 26, 2008: 12:00 AM
Room: Room 207
Background: Since 2000 we observed the rapid emergence of azole-resistance in A. fumigatus (A.f.). We performed a prospective multicenter surveillance study to determine the prevalence of azole-resistance in Aspergillus (Asp.) sp. in the Netherlands. Methods: Between May 2007 and April 2008 clinical microbiology laboratories of the eight Dutch Univ. Med. Cent. screened all Asp. isolates for resistance to itraconazole (ITZ) using Sabouraud agar slants supplemented with 4 mg/l of ITZ. Patient and isolate characteristics were collected. Phenotypic susceptibility profile and the mechanism of resistance were determined for resistant isolates. Results: In total 1085 Asp. isolates were included. 940 (87%) of isolates were identified as A.f. and 145 (13%) as other Asp. sp.. The overall prevalence of ITZ-resistance in A.f. was 4.4%. In two centers the prevalence was 0.6 and 1.5%, whilst in the others it ranged between 2.5 and 6.6%. Also resistance for vori- and posaconazole was seen in resp. 91 and 83% of ITZ-resistant isolates. In 95% of ITZ-resistant A.f. isolates a L98H substitution with a 34 bp tandem repeat, as previously described, was found. Whether patients were more likely to harbor an ITZ-resistant isolate than others seemed significantly dependent on their underlying disease (P <0.05), a prevalence of 9.6% was found amongst patients with hematologic and malignant diseases. Conclusions: Our results show that ITZ-(cross)resistance in A.f. is wide-spread in the Netherlands.
B Rijnders1, C Visser2, E Mattsson3, E Snelders4, E Kuijper5, F van Tiel6, G Kampinga7, J van der Linden8, P Verweij4, W Melchers, PhD4, Y Debets9 and  J. W. M. van der Linden, None., (1)Erasmus Medical Center, (2)Amsterdam Medical Center, (3)University Medical Center Utrecht, (4)Radboud University Nijmegen Medical Center, (5)Leiden University Medical Center, (6)University Medical Center Maastricht, (7)University Medical Center Groningen, (8)Radboud University Nijmegen Medical Center, Nijmegen, Netherlands, (9)VU-Medical Center