To discuss how room design and conversion may influence the association between negative-pressure ICU rooms and pulmonary aspergillosis in patients with COVID-19.
Approach:
Prior room-conversion report: The authors describe a 2020 ICU report in which rooms were converted from positive to negative pressure and Aspergillus fumigatus was detected in room air and in some patients.
Comparison with published studies: The letter contrasts that experience with Kreitmann et al.’s multicenter observational study and discusses findings from Biebelberg et al. and commentary by Schaffzin et al.
Key Findings:
In the authors’ 2020 report, probable or proven pulmonary aspergillosis occurred in 6 of 26 patients, and 2 additional patients were colonized by A. fumigatus. Airborne A. fumigatus declined after disinfection and pressure changes, but concurrent antifungal pr…
Kreitmann et al. reported lower 60-day cumulative incidence of probable invasive pulmonary aspergillosis under FUNDICU criteria among 1,233 mechanically ventilated patients exposed to negative-pressure rooms across 75 ICUs. The observational association does n…
The association was not significant for putative IPA under AspICU criteria or for a composite endpoint of putative IPA and Aspergillus colonization, although estimates pointed in the same direction.
Mycological testing was less frequent in negative-pressure rooms: bronchoalveolar lavage with mycological testing was performed in 5.8% versus 22.3%, and serum galactomannan testing in 14% versus 26%, potentially contributing to underdiagnosis.
Biebelberg et al. observed higher hospital-acquired Aspergillus rates at a hospital using negative-pressure rooms more extensively; rates decreased after use was reduced. These observations do not establish causality.
Interpretation:
The authors propose that purpose-built negative-pressure rooms may differ from rooms converted from positive pressure. Room configuration, airtightness, pressure zoning, ventilation, filtration, exhaust, and environmental fungal reservoirs may affect exposure; the available studies do not resolve whether conversion of rooms not designed for negative pressure increases risk.
Limitations:
The 2020 report cannot separate the effects of pressure modification from antifungal prophylaxis.
Kreitmann et al. lacked detailed assessments of room pressure, ventilation and filtration performance, environmental fungal burden, and anteroom configuration.
Differing rates of mycological investigation may have caused underdiagnosis and differential case detection.
The cited observational findings do not demonstrate causality.
Conclusion:
The authors call for future studies to assess room architecture, anteroom configuration, pressure gradients, ventilation and filtration, alongside standardized mycological and environmental surveillance.
