Azole Resistance of Aspergillus fumigatus in Immunocompromised Patients with Invasive Aspergillosis.

Abstract

To the Editor: Alanio et al. comment that the prevalence of azole-resistant Aspergillus disease may differ, depending on location of the hospital where patients are admitted and the patients’ underlying disease (1). Determining local or regional epidemiology, especially in areas where azole-resistant isolates are found in the environment, is indeed important. These isolates commonly harbor the TR34/L98H or TR46/Y121F/T289A resistance mechanism. Patients may inhale azole-resistant spores in the air and subsequently develop azole-resistant disease, even when they have never been treated with azoles (2). Although risk for inhalation of azole-resistant Aspergillus spores arguably might be similar for all patients, surveillance of Aspergillus isolates in the Netherlands indicates that resistance rates vary among hospitals. When all A. fumigatus isolates cultured from patients were investigated for azole resistance, resistance rates in the Netherlands ranged from 4.3% to 19.2% in 2013 and 3.8% to 13.3% in 2014 (3). The highest and lowest resistance rates were found in hospitals only 39 km from each other, supporting the observation made by Alanio et al. about variations in prevalence of azole-resistant Aspergillus disease (1).