A strain of Stachybotrys chartarum was recently isolated from the lung of a pulmonary hemorrhage and hemosiderosis (PH) patient in Texas (designated the Houston strain). This is the first time that S. chartarum has been isolated from the lung of a PH patient. In this study, the Houston strain and 10 strains of S. chartarum isolated from case (n ؍ 5) or control (n ؍ 5) homes in Cleveland were analyzed for hemolytic activity, siderophore production, and relatedness as measured by random amplified polymorphic DNA analysis.The fungus Stachybotrys chartarum (Ehrenb. ex Link) Hughes(ϭ S. atra Corda) has been associated with a number of human health problems, including potentially fatal pulmonary hemorrhage and hemosiderosis (PH) in infants (3,4,5,9,10,16). Recently, Elidemir et al. (6) isolated a strain of S. chartarum (designated here as the Houston strain) from the lungs of a child with progressive respiratory symptoms and PH. S. chartarum was also found in the child's water-damaged home. The child recovered after removal from the house and subsequent remediation of the home.In this study, hydroxamate-type siderophore production and hemolytic activity by case and control strains from Cleveland were quantified and compared to those of the Houston strain. Random amplified polymorphic DNA (RAPD) analysis of the Houston strain was also compared with those of case and control strains from Cleveland (22).Quantification of siderophore production and hemolytic activity by S. chartarum when incubated with human blood. Five strains of S. chartarum isolated from PH control houses in and five from case houses (51-08, 51-11, 58-02, 58-06, and 63-07) (15) and the Houston strain were used. The strains of S. chartarum were grown on wet wallboard pieces as previously described (22). Human blood used in this study was taken from one of the authors by his physician using 7-ml vacuum tubes containing sodium heparin (Becton Dickinson, Franklin Lakes, N.J.), and the tubes were then refrigerated overnight. The next day the plasma was separated from the packed red blood cells (RBC) and the buffy coat containing the white blood cells was removed and discarded. To 250 ml of Trypticase soy broth (Becton Dickinson, Sparks, Md.) was added 1.5 ml of the packed RBC and 2 ml of plasma, and then the sample was mixed continuously while 10-ml aliquots were dispensed into 50-ml polypropylene tubes (Corning Inc., Corning, N.Y.). Approximately 4 ϫ 10 4 conidia of each strain were added to each of three replicate tubes. The tubes were placed on an incubatorshaker