Identification and Distribution of Potentially Azole‐Resistant Airborne Fungi in Outdoor Environments of the Basque Country

Airborne fungi are ubiquitous microorganisms in the environment, and some of them are known opportunistic pathogens. In recent years, azole resistance, which can have a clinical or environmental origin, has become a critical issue. Four environmental samplings were performed to assess the prevalence and diversity of potentially azole-resistant fungi in three areas (hospital surrounding, rural and urban) from the Basque Country. The microbial concentration varied from 40 to 3670 CFU/m³, depending on the location and sampling. The CFU/m³ count on plates incubated with voriconazole at 37°C was only three times lower than that of plates incubated without the antifungal, suggesting many 37°C-growing fungi might be triazole-resistant. Three hundred and twenty one potentially resistant isolates were identified, belonging to 21 genera and 55 species. Alternaria (62.31%) and Talaromyces (18.69%) were the predominant genera, with Alternaria infectoria (47.19%) being the most abundant species. Overall, the two coastal provinces (Bizkaia and Gipuzkoa) showed the most similarity. The rural area exhibited the highest alpha diversity values for each province, whereas samples from this area were more alike in terms of beta diversity. PCoA analysis indicated that sampling points were clustered by samplings or provinces. This study provides the first characterisation of the outdoor environment from the Basque Country and highlights the importance of determining the prevalence of potentially azole-resistant isolates.