PROSPECTIVE MULTICENTER STUDY ON AZOLE RESISTANCE IN ASPERGILLUS ISOLATES FROM SURVEILLANCE CULTURES IN HAEMATOLOGICAL PATIENTS IN ITALY

Abstract Objectives This study was conducted to assess the prevalence of azole resistance inAspergillus isolates from patients with haematological malignancies or undergoing haematopoietic stem cell transplantation and to identify the molecular mechanism of resistance. Methods In the 28-month prospective study involving 18 Italian centres,Aspergillus isolates from surveillance cultures were collected, screened for azole resistance, and mutations in cyp51A gene were identified. Resistant isolates were genotyped by microsatellite analysis and the allelic profiles compared with those of resistant environmental and clinical isolates from the same geographical area previously genotyped. Results 292Aspergillus isolates from 228 patients were collected. The isolates belonged mainly to the section Fumigati (45.9%), Nigri (20.9%), Flavi (16.8%), Terrei (4.8%). Three isolates showed itraconazole resistance: A. fumigatus sensu stricto, A. lentulus (section Fumigati), and A. awamori (section Nigri). The itraconazole resistance rate was 1% and 1.48% considering all Aspergillus spp. isolates and Aspergillus section Fumigati, respectively. The prevalence of azole resistance among all the patients was 1.3%. Among patients harbouring A. fumigatus sensu stricto isolates, the resistance rate was 0.79%. The A. fumigatus isolate, with TR34/L98H mutation, was genotypically distant from environmental and clinical strains previously genotyped. Conclusions In this study, theAspergillus azole resistance rate was 1% (3/292). In addition to A. fumigatus sensu stricto, A. lentulus and A. awamori azole resistant were identified. Therefore, it is important a correct identification at species level to better address a rapid therapy, to understand quickly the shift towards cryptic species and to have an updated knowledge of the local epidemiology.