Localization of the vegetative form of Clostridium tetani in mouse tumors following intravenous spore administration.

Summary Mice bearing spontaneous mammary carcinomas, transplanted mammary carcinomas, hepatomas, and sarcomas were given intravenous injections of Cl. tetani spores in doses ranging from 9,000 to 150,000 spores per mouse. All the treated animals died of tetanus 48 hours after spore injection, indicating the germination of the tetanus spores and the formation of the lethal toxin. Nontumor-bearing mice similarly treated remained asymptomatic throughout the 40-day observation period. At various time intervals after spore injection, microscopic examination of the tumors and organs of the Cl. tetani spore-treated, antitoxin-protected mice bearing the previously described tumors revealed that germination of the Cl. tetani spores occurred only in the cancerous tissue and that the vegetative (antigenic) form of the organism remained within the tumor area. Cultures made from portions of the tissues examined microscopically further confirmed spore germination and the exclusive localization of the vegetative form of Cl. tetani in the cancerous sites and demonstrated that this antigen was present in a high concentration.