RATIONALE: Ottawa County in northeast Oklahoma has a 13.4% asthma rate, while the average for the state is 7.2%. Possible risk factors include a large compost facility, and a previous study found elevated Aspergillus fumigatus levels close to the facility. The present project was undertaken to estimate exposure to A. fumigatus in the county and determine the source using DNA fingerprinting. METHODS: Air samples were collected for 15 weeks from 5 towns in Ottawa County using Anderson N-6 samplers with malt extract agar (MEA). Control samples were collected from Tulsa, 144 km upwind. Cultures were incubated at 45Â°C for 48 hours and all A. fumigatus identified and subcultured. Samples of compost were purchased from the facility and dilution plated onto MEA. Plates were incubated and A. fumigatus subcultured as above. DNA was isolated from all isolates using EZNA kit, amplified by PCR, and fingerprinted using STRAf2A microsatellite oligonucleotide pair. RESULTS: Aspergillus fumigatus was isolated 7 times during air sampling in Ottawa County with concentrations as high as 277 colony forming units (CFU)/m3; in Tulsa, the fungus was isolated 5 times with the peak of 70 CFU/m3. Concentrations of A. fumigatus in compost were variable with a mean of 6975 CFU/g. Microsatellite analysis identified 9 distinct strains from compost and air samples. Strains isolated from Ottawa County air samples were also isolated from compost. By contrast, Tulsa isolates were genetically different from Ottawa air or compost samples. CONCLUSIONS: Sensitive individuals in Ottawa County are exposed to Aspergillus fumigatus spores originating from a local compost facility.
Full conference title:
American Academy of Allergy Asthma & Immunology
- AAAAI 2010 (66th)