# Hospital Indoor Air as a Reservoir of Opportunistic Filamentous Fungi: Species Diversity and Antifungal Susceptibility

## TL;DR

This study found diverse filamentous fungi in hospital air, including some resistant to antifungal drugs, highlighting the need for better monitoring and ventilation to protect vulnerable patients.

## Contribution

The study identifies emerging and resistant Aspergillus species in hospital air and evaluates their antifungal susceptibility, emphasizing the need for improved infection control.

## Key findings

- Penicillium, Cladosporium, and Aspergillus were the most prevalent airborne fungi in hospital wards.
- Resistance to itraconazole was detected in some Aspergillus isolates, and emerging species showed elevated antifungal resistance.
- Anidulafungin showed low resistance across all isolates, suggesting potential as a treatment option.

## Abstract

Filamentous fungi are common airborne contaminants in hospitals, posing significant risks to immunocompromised patients. This study assessed the diversity, seasonal distribution, and antifungal susceptibility of airborne filamentous fungi, with a focus on Aspergillus spp., in two inpatient wards of a tertiary hospital in southeastern Brazil. Air samples were collected seasonally from November 2022 to September 2023 using a six-stage Andersen sampler. Fungal isolates were identified based on macro- and micromorphological characteristics, and Aspergillus spp. were further characterised by β-tubulin gene sequencing. In vitro susceptibility to amphotericin B (AMB), itraconazole (ITR), voriconazole (VOR), posaconazole (POS), and anidulafungin (AFG) was evaluated following CLSI guidelines. A total of 583 filamentous fungi were isolated, with Penicillium, Cladosporium and Aspergillus as the most prevalent genera. Fungal concentrations were higher in humidified air and decreased after installation and maintenance of the air-conditioning system. Fourteen Aspergillus species were identified across eight sections, including emerging and cryptic taxa such as A. subramanianii, A. sclerotiorum and A. alboviridis. Resistance to ITR was detected in one isolate of A. fumigatus and one of A. flavus, while isolates from emerging species of the section Circumdati exhibited elevated MICs for AMB and triazoles. All isolates demonstrated low AFG MECs. The study highlights the importance of routine environmental surveillance and antifungal susceptibility testing in hospital settings. The detection of potentially resistant Aspergillus species in hospital air emphasises the need to enhance ventilation, monitoring, and diagnostic capabilities to mitigate the risks of healthcare-associated fungal infections.