Epidemiology, antifungal susceptibility and biological characteristics of clinical Aspergillus fumigatus in a tertiary hospital

Azole resistance in Aspergillus fumigatus poses a significant clinical challenge globally. In this study, we analyzed 307 clinical A. fumigatus isolates from General Hospital of Ningxia Medical University in China, collected between July 2023 and July 2024, to explore their susceptibility profiles, genotypic characteristics and biological traits. The overall frequency of azole resistance among clinical isolates in Ningxia province was found to be 1.20% (7 azole-resistant A. fumigatus, designated AF1-AF7), each exhibiting distinct phenotypes in terms of azole resistance, spore viability, and resilience to environmental stress. Among these strains, the cyp51A mutations predominantly included TR43/L98H, while the hmg1 mutations were primarily S212P/Y564H. Additionally, novel mutations were discovered in cyp51B, specifically the t-215c point mutation and a base deletion (gatgccta) in the - 213 to - 206 region. The AF3 strain demonstrated the highest spore activity and anti-SDS efficacy. In contrast, the AF1 and AF2 strains were resistant to three azoles and also exhibited resistance to Menadione, similar to AF7. Notably, six out of the seven strains displayed resistance to NaCl and KCl, indicating a strong tolerance to saline conditions. These findings suggest that azole-resistant strains possess varying degrees of resistance to environmental stressors, implying that they may adapt to their surroundings through different evolutionary pathways, which could complicate clinical treatment strategies. Effective surveillance and control strategies are essential to control the widespread prevalence of azole-resistant A. fumigatus and to reduce the risk of infection in patients.