Azole-resistant Aspergillus fumigatus: poultry farms and schools as sentinels in Portugal

Background

Azole resistance in Aspergillus fumigatus (ARAf) is a growing global health threat, with environmental selection driven by agricultural fungicide use now recognised by the 2025 joint EFSA/ECDC/EMA/ECHA/EEA report. In Portugal, environmental ARAf remains under characterised, with prior reports limited to dairy and waste-sorting occupational settings. No study has simultaneously examined resistance across agricultural and educational environments.

Methods

Two cross-sectional environmental surveillance studies were conducted in Portugal using harmonised methodology (EUCAST 10.2/9.4). Study 1 included 11 primary schools in the Lisbon metropolitan area (active air sampling, electrostatic dust collectors, settled dust filters; n = 164 Aspergillus section Fumigati isolates). Study 2 included 14 poultry pavilions in Madeira Island (bedding, feed, air, workers ‘masks; n = 168 Aspergillus section Fumigati isolates). Thermotolerant isolates were screened for azole resistance (itraconazole, voriconazole, posaconazole). Resistant isolates were molecularly identified by sequencing.

Results

In schools, 151/164 isolates (92%) were thermotolerant; 28 showed potential azole resistance, 67.9% with pan-azole resistance. All were confirmed as A. fumigatus sensu stricto. In poultry farms, 168/176 isolates (95%) were thermotolerant; 7 showed potential azole resistance, all with pan-azole resistance. All were confirmed as A. fumigatus sensu stricto. Dust-based matrices (EDC/settled dust; air/bedding) were the main reservoirs in each setting.

Conclusions

These findings, from geographically and functionally distinct settings, suggest Portugal may constitute an underrecognized multi-environment hotspot for thermotolerant ARAf. The convergence of resistance in agricultural and community environments reinforces the urgency of integrated One Health surveillance encompassing non-occupational settings, in alignment with current European regulatory priorities.

Key messages

• Portugal shows high azole-resistant A. fumigatus prevalence in both schools and poultry farms, suggesting a multi-environment hotspot requiring urgent One Health surveillance.

• Pan-azole resistance in non-clinical indoor settings signals the need to expand European AMR surveillance beyond known agricultural hotspots.