Acute vegetative endocarditis caused by the diphtheria bacillus is of infrequent occurrence, the literature up to the present time containing reports of only six cases. The micro-organisms isolated in three of these cases had all the cultural and morphologic characteristics of Bacillus diphtheriae but did not produce a toxin in amounts sufficient to be lethal for guinea-pigs. In the other three cases reported the bacilli were characteristic of B. diphtheriae morphologically and culturally as well as in their lethal effect when broth cultures were injected into guinea-pigs.
The nontoxic bacilli simulating B. diphtheriae were isolated at autopsy in the cases reported by Howard1 in 1893 and by Roosen-Runge2 in 1903 and 1925. Herzog3 in 1918 was the first to isolate a strain of B. diphtheriae from the blood in pure culture which was lethal for guinea-pigs when 1 cc. of a three day broth culture was inoculated