The primary objective of this project is to determine if there is an association between bacteremia with members of the family Bacteroidaceae or organisms of "L-type" morphology and thromboembolic disease. Blood cultures employing hypertonic media have been obtained from 44 patients with thromboembolic disease and 36 controls with no history of thrombophlebitis, or site of infection. Blood cultures obtained from four (17%) of 23 patients with acute thromboembolic disease and 10 (48%) of 21 patients with recurrent thromboembolic disease were positive of organisms of "L-type" morphology. The isolates grew only under anaerobic conditions and did not revert to typical bacterial forms. Blood cultures from the control group were negative for bacterial growth. These results suggest that there may be an etiologic relationship between Bacteroides bacteremia and thromoembolic disease. We are currently attempting to determine if there are clinical features unique to those patients with thromboembolic disease who had positive blood cultures. In addition, the mechanisms by which cell wall components of gram-negative anaerobic microorganisms affect coagulation and the host's response to bacteremia with members of the family Bacteroidaceae will be investigated.