Evaluation of antimicrobial agents in the rabbit model of endocarditis.

The placement of a sterile polyethylene catheter in the heart of a rabbit results in nonbacterial thrombotic endocarditis characterized by an accumulation of fibrin strands, erythrocytes, and platelets that adhere to the endothelial surface. These elements form a nidus where a pathogen, when introduced by injection, lodges, multiples, and develops vegetations typical of infective endocarditis. In the rabbit model, endocarditis induced by Staphylococcus aureus or viridans group Streptococcus resembles the human disease in clinical and bacteriologic features and in response to antimicrobial therapy. The rabbit model thus affords a means of evaluating the therapy of endocarditis. The end points of therapeutic response are culture-negative vegetations and failure to relapse. On the basis of these criteria vancomycin was found to be more rapidly effective in curing an infection caused by a single strain of S. aureus than penicillin or cefazolin and as effective as a combination of penicillin and gentamicin.