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

## TL;DR

This study identifies and analyzes the distribution of potentially azole-resistant fungi in outdoor environments across the Basque Country.

## Contribution

The paper provides the first characterization of potentially azole-resistant fungi in the Basque Country's outdoor environments.

## Key findings

- Alternaria and Talaromyces were the most prevalent genera, with Alternaria infectoria being the most abundant species.
- Rural areas showed the highest alpha diversity, while coastal provinces (Bizkaia and Gipuzkoa) were most similar in fungal distribution.
- Fungi grown at 37°C on voriconazole plates suggest a high prevalence of triazole-resistant species.

## Abstract

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.

Air samples collected at three areas in each province of the Basque Country (Spain) were incubated at 25°C and 37°C for Sabouraud plates (SAB) and at 37°C for plates supplemented with voriconazol (SAB‐VCZ). The potentially resistant isolates from SAB‐VCZ plates were identified and their abundance and diversity were determined.