Recovery and identification of fungal spores from the nasal cavity

Recent data suggests that germination of fungal spores increases their release of allergen. We assessed the species and germination state of spores recovered by nasal lavage after natural exposure. Nasal lavage was performed on 12 adults at 3 intervals: (1) at the start of the experiment, (2) after 1 hour in a clean indoor environment, and (3) after 1 hour outdoors near a grassed sports field. Personal aerosol samplers (IOM) were run concurrently. One portion of lavage fluid was treated with Sputolysin and plated onto V8 (V8) and Rose-Bengal Chloramphenicol (RB) agar for identification of viable fungal colonies. Another portion was treated immediately with Kathon CG to prevent in vitro germination and stained by Periodic Acid Schiff (PAS) to allow identification of germinated and non-germinated spores. By culture, the median number of viable fungi recovered after 1 hour outdoors was significantly greater than after 1 hour indoors on both V8 (p=0.0029) and RB (p=0.0020). On V8 media, colony counts were (25th percentile, median, 75th percentile): Sample (1) (0,1,4.5), Sample (2) (0,1,1.25) and Sample (3) (2,6.5,14.25). Median IOM fungal counts from outdoors were significantly greater than from indoors (p=0.0005) and correlated to numbers of fungi recovered on each media. The major species recovered were Cladosporium, Epicoccum, Penicillium, Aspergillus and yeasts. PAS staining showed that germinating and non-germinating spores were present in the nasal cavity. The number of fungi recoverable from the nasal cavity reflects environmental exposure. Viable and germinating fungi can be present in the nasal cavity.