Abstract
Rosenbach 1 produced experimental bacterial endocarditis in dogs by passing an instrument down the right carotid artery to wound the valves. Most of his. experiments on dogs and rabbits produced aseptic lesions but 2 of his dogs developed large vegetations on the aortic valve and numerous septic infarcts and petechial hemorrhages in various organs. Colonies of micrococci, apparently staphylococci, were demonstrated in these lesions. Ever since that pioneer observation there has prevailed the idea that some accessory injury of the endocardium is necessary in addition to the introduction of bacteria into the blood-stream, if one is to succeed in causing experimental endocarditis. Welch, Murdock and Ferguson 2 punctured the heart and then rotated the needle to produce a preliminary endocardial wound before introducing their bacteria intravenously or into the pulp of a tooth. In addition they resorted to accessory respiratory infection and dietary restriction to lower the resistance of their animals. In this way they succeeded in producing gross endocardial vegetations in 20% of their rabbits inoculated with endocarditis-streptococci. Dietrich 3 has introduced various substances parenterally to injure the valves and then has injected staphylococci or colon bacilli to produce the vegetations. British investigators, however, have been successful without the preliminary injury to the endocardium. Apparently the first success of this kind was obtained by Dreschfeld, 4 who succeeded by the simple intravenous injection of endocarditis-streptococci into rabbits long before Streptococcus viridans had been distinguished from other streptococci. More recently Lloyd-Jones 5 has made a most significant contribution. He was able to produce endocarditis in rabbits with great regularity by repeated daily intravenous injection of hemolytic streptococci and particularly by such injection of serum-broth cultures of viridans types of streptococci obtained from the human intestine and uterine cervix.
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