Comparison of Detection Methods for Aspergillus fumigatus in Environmental Air Samples in an Occupational Environment

Abstract

Methods to study occupational exposures to fungi and fungal materials in facilities where the dominant exposure is the pathogenic and allergenic fungus Aspergillus fumigatus are lacking. Air samples were collected near a conveyor in a wood chip recycling plant to compare methods that might be used to assess exposure to A. fumigatus or suitable proxies. These included total dust mass, total intact spores, culturable propagules growing > 35°C, ergosterol, A. fumigatus allergen Asp f1, and quantitative polymerase chain reaction for A. fumigatus. Of these measurements, Asp f1 showed the most promise based on its relative response to measurements where there is a long history of use in industrial hygiene practice (total mass, ergosterol, total intact spores, culturable propagules).

Keywords:

• Aspergillus fumigatus
• bioaerosols
• ergosterol
• Asp f1
• QPCR
• forest products

ACKNOWLEDGMENTS

We thank Robert Fisher, Chin Yang, and Jack Halsley for their helpful advice, and Weyerhaeuser Company for the opportunity to take samples.

The project was funded by National Council for Air Stream Improvement and an Natural Sciences & Engineering Research Council grant to JDM. Expert technical support was provided by Don Belilse and Jonathan Plett. A critical review of the manuscript by Robert Fisher was much appreciated.

Notes

^A Arithmetic and geometric means and ranges presented in results section.

^B Estimated using per spore ergosterol values for related aspergillii; Miller and Young.^{( 16 )}