Epidemiology of invasive aspergillosis and triazole-resistant Aspergillus fumigatus in patients with haematological malignancies: a single-centre retrospective cohort study.

Objectives: To investigate the epidemiology and clinical relevance of triazole resistance among patients undergoing treatment for haematological malignancies who are at risk of invasive aspergillosis (IA).

Methods: This was a retrospective cohort study for which the records of consecutive patients given chemotherapy for AML or myelodysplastic syndrome (MDS) or who had received an allogeneic HSCT from 2006 to 2012 were reviewed for IA. Triazole resistance was detected by the VIPcheck™ screening method and confirmed by determining the MIC by EUCAST methodology.

Results: A total of 432 patients were included, comprising 182 (42.1%) patients who had undergone chemotherapy for AML or MDS, and 250 (57.9%) patients who had undergone an allogeneic HSCT. Probable or proven IA was diagnosed in 36 cases (8.3%, 95% CI 6.0%-11.4%). Of these, 12 (33.3%) were based on recovery of Aspergillus fumigatus from sputum, bronchoalveolar lavage or biopsy, and triazole resistance was found in 2 instances. A. fumigatus was also recovered from one or more specimens from 13 patients without probable or proven IA. Triazole resistance was documented for three patients. The survival rate of patients with IA caused by voriconazole-resistant isolates could not be assessed.

Conclusions: The overall frequency of voriconazole-resistant IA among patients at high risk was low. However, the rate of triazole resistance may have been underestimated by the low detection rate based on recovery of A. fumigatus. Alternative diagnostic tests, such as PCR-based assays, may prove better at detecting IA due to triazole-resistant A. fumigatus.