In 1928 Gregory Shwartzman described for the first time a new phenomenon which consisted in the following: Rabbits received an intradermal injection of 0.25 cc. of undiluted filtrate of five-to seven-day-old broth culture of a given microörganism (preparatory factors) and then twenty-four hours later were injected intravenously with a given amount of the filtrate (reacting factors). Four to five hours after the intravenous injection, there developed severe hemorrhagic and necrotic reactions at the site of the intradermal injection.
Observations previously reported by me suggested strongly that the Shwartzman phenomenon offered an opportunity to extend our knowledge concerning the hitherto unknown rôle of B. typhosus and B. paratyphosus toxic substances in human infections. In these investigations I attempted first to determine whether substances similar to those necessary for the Shwartzman phenomenon could be discovered in patients suffering from B. typhosus and B. paratyphosus infections.