Beneficial effect of combination antiplatelet therapy on the development of experimental Staphylococcus aureus endocarditis

Previous studies in our laboratory have shown that antiplatelet agents, asp irin and ticlopidine, in clinically relevant concentrations influence the d evelopment and treatment of experimental endocarditis. To study the influen ce of combination antiplatelet treatment on the development of aortic veget ations, infected animals received either aspirin alone, ticlopidine alone, aspirin plus ticlopidine or no antiplatelet therapy. The combination antipl atelet treated group had a statistically significant (P = 0.043) reduction of the vegetative weight as compared with the untreated controls. While bot h the single antiplatelet agent groups showed a reduction in the size of th e vegetation, neither achieved statistical significance. None of the treatm ent groups significantly altered the bacterial density relative to untreate d controls. These findings reveal that the combination of aspirin and ticlo pidine, two potent inhibitors of platelet aggregation with different mechan isms of action, act synergistically to optimally reduce the weight of aorti c valve vegetations. (C) 1999 Published by Elsevier Science B.V. and Intern ational Society of Chemotherapy. All rights reserved.