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Fungal colonization of air filters from hospitals
R B Simmons1, D L Price, J A Noble
1Department of Biology, Georgia State University, Atlanta 30302-4010, USA. biorbs@panther.gsu.edu
Abstract:
Air filters of various types, selected on the basis of discoloration, were collected from the primary and secondary filter banks of the heating, ventilating, and air-conditioning systems in seven hospitals in the eastern United States and examined with direct microscopy for fungal colonization. Microscopic observations and culture results showed that filters from five of the hospitals were colonized with fungi including species of Acremonium, Alternaria, Aspergillus, Cladosporium, Epicoccum, Penicillium, and Rhinocladiella, and a Beauveria-like fungus. Several of these commonly airborne species, e.g., Epicoccum purpurescens (syn. E. nigrum) and Rhinocladiella sp., had not been previously reported to colonize (with conidiogenesis) air filters.
Insights
Hospital air filters were examined for fungal colonization. Five of seven tested filters showed significant fungal growth, including species not previously known to colonize air filters.
Area of Science:
- Environmental microbiology
- Mycology
- Indoor air quality
Background:
- Hospital heating, ventilating, and air-conditioning (HVAC) systems circulate air, potentially impacting indoor environments.
- Air filters are critical components of HVAC systems, designed to capture airborne particles.
- Fungal contamination of air filters can affect indoor air quality and potentially pose health risks.
Purpose of the Study:
- To investigate fungal colonization of air filters from hospital HVAC systems.
- To identify fungal species present on discolored air filters.
- To determine if previously unreported fungal species colonize air filters.
Main Methods:
- Air filters were collected from primary and secondary filter banks in seven US hospitals.
- Filters were selected based on visible discoloration.
- Direct microscopy and culture techniques were used to examine filters for fungal colonization.
Main Results:
- Fungal colonization was detected in air filters from five out of seven hospitals.
- Identified fungi included common airborne species such as Acremonium, Aspergillus, Cladosporium, and Penicillium.
- Species like Epicoccum purpurescens and Rhinocladiella sp. were found to colonize air filters, a novel finding.
Conclusions:
- Hospital air filters can serve as substrates for fungal growth.
- The presence of diverse fungal species, including novel colonizers, highlights potential implications for indoor air quality in healthcare settings.
- Further research is warranted to understand the clinical significance of fungal colonization on air filters.