Hemolysis, Toxicity, and Randomly Amplified Polymorphic DNA Analysis of Stachybotrys chartarum Strains

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°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°C. Five of the Cleveland strains (all from case homes) showed hemolytic activity at 37°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 μg 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.