Exploring Factors Driving the Uneven Distribution of Aspergillus terreus in an Austrian Hotspot Region

<i>Aspergillus terreus</i> is an opportunistic fungal pathogen and a major cause of aspergillosis. Its clinical significance is heightened by high mortality rates, dissemination, and resistance to amphotericin B, complicating treatment. The present study investigates the distribution of <i>A. terreus</i> in Tyrolean (Austria) soils and explores potential environmental factors influencing its uneven prevalence. Soil samples from the eastern and western parts of Tyrol were analyzed using soil extraction plating, the soil immersion tube method, and <i>A. terreus</i>-specific qPCR. The results revealed a significantly higher prevalence of <i>A. terreus</i> in the eastern region. Soil parameters, including pH, moisture, organic matter, total carbon, and nitrogen, were assessed for potential correlations with fungal distribution. The presence of <i>A. terreus</i> was significantly associated with lower pH, decreased total carbon and nitrogen, and lower soil density. Random sampling across Austria indicated a lower environmental frequency of <i>A. terreus</i> outside of Tyrol. The susceptibility profiles of amphotericin B, posaconazole, isavuconazole, and voriconazole were determined according to EUCAST guidelines, showing that 98.3% of isolates were wild type for amphotericin B, 100% wild type for voriconazole, 100% resistant to posaconazole, and 87.2% resistant to isavuconazole.