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Hemolysis, toxicity, and randomly amplified polymorphic DNA analysis of Stachybotrys chartarum strains
S J Vesper1, D G Dearborn, I Yike
1National Exposure Research Laboratory, U.S. Environmental Protection Agency, Cincinnati, Ohio 45268, USA. Vesper.Stephen@EPA.gov
Abstract:
Stachybotrys chartarum is an indoor air, toxigenic fungus that has been associated with a number of human and veterinary health problems. Most notable among these has been a cluster of idiopathic pulmonary hemorrhage cases that were observed in the Cleveland, Ohio, area. In this study, 16 strains of S. chartarum isolated from case (n = 8) or control (n = 8) homes in Cleveland and 12 non-Cleveland strains from diverse geographic locations were analyzed for hemolytic activity, conidial toxicity, and randomly amplified polymorphic DNA banding patterns. In tests for hemolytic activity, strains were grown at 23 degrees C on wet wallboard pieces for an 8-week test period. Conidia from these wallboard pieces were subcultured on sheep's blood agar once a week over this period and examined for growth and clearing of the medium at 37 or 23 degrees C. Five of the Cleveland strains (all from case homes) showed hemolytic activity at 37 degrees C throughout the 8-week test compared to 3 of the non-Cleveland strains. Five of the Cleveland strains, compared to two of the non-Cleveland strains, produced highly toxic conidia (>90 microgram of T2 toxin equivalents per g [wet weight] of conidia) after 10 and 30 days of growth on wet wallboard. Only 3 of the 28 strains examined both were consistently hemolytic and produced highly toxic conidia. Each of these strains was isolated from a house in Cleveland where an infant had idiopathic pulmonary hemorrhage.
Insights
Toxigenic fungus Stachybotrys chartarum strains from Cleveland homes, particularly those with infant idiopathic pulmonary hemorrhage, exhibited higher hemolytic activity and conidial toxicity. This highlights potential indoor air health risks.
Area of Science:
- Environmental microbiology
- Mycology
- Toxicology
Background:
- Stachybotrys chartarum is a toxigenic indoor fungus linked to human and animal health issues.
- A notable association exists with idiopathic pulmonary hemorrhage cases in infants in the Cleveland, Ohio area.
Purpose of the Study:
- To analyze Stachybotrys chartarum strains for hemolytic activity, conidial toxicity, and genetic diversity.
- To compare strains isolated from case homes (idiopathic pulmonary hemorrhage) versus control homes in Cleveland and other geographic locations.
Main Methods:
- 16 Stachybotrys chartarum strains from Cleveland (8 case, 8 control) and 12 non-Cleveland strains were tested.
- Hemolytic activity was assessed on sheep's blood agar after 8 weeks of growth on wet wallboard.
- Conidial toxicity was quantified by measuring T2 toxin equivalents.
Main Results:
- Five Cleveland strains from case homes showed consistent hemolytic activity at 37°C, compared to three non-Cleveland strains.
- Five Cleveland strains produced highly toxic conidia (>90 µg T2 toxin equivalents/g), versus two non-Cleveland strains.
- Three strains, consistently hemolytic and highly toxic, were isolated from Cleveland homes with infant idiopathic pulmonary hemorrhage.
Conclusions:
- Strains of Stachybotrys chartarum from Cleveland case homes demonstrated increased hemolytic activity and conidial toxicity.
- These findings suggest a potential link between specific toxigenic fungal strains and idiopathic pulmonary hemorrhage in infants.
- Further research is warranted to understand the pathogenicity and environmental factors contributing to these health outcomes.
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