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

Studies of the effect of bacteria on neoplasms are among the oldest approaches to the problem of cancer therapy. In 1868, Busch (2) reported tem porary clinical improvement in two patients with sarcoma who developed concurrent erysipelas. Subsequent studies, identifying streptococci and other micro-organisms involved in tumor destruc tion, ascribed their effect to a toxic bacterial prod uct (3) and established an investigative pattern that has dominated the bacterial approach to the tumor problem in the intervening years. Perhaps as a result of this emphasis on bacterial products capable of eliciting a deleterious effect on the tu mor cell, little attention has been given to the pos sibility of localizing1 the bacteria per se in the tu mor site. Although it is well recognized that bac teria are sometimes found in tumors, no consist ency regarding their presence or type has been ob served, and there are, to the best of our knowledge, no previous reports demonstrating that either these chance contaminants or the intentional sys temic administration of bacteria result in exclusive localization of the organism in the tumor site. The cancer studies involving fungi and protozoa have been similarly oriented to the concept of a tumor-destructive microbiologic product, and the exclusive localization of the test organism in tu mors has not been reported. All these various microbiologic technics have recently been re viewed by Reilly (7). In recent viral studies, on the other hand, the establishment of the virus in the tumor tissue has been an important aspect of the investigation, and there are numerous reports of attempts to adapt the virus to the malignant cell (6, 8). This adapta tion, based on the concept of an intrinsic difference between normal and neoplastic cells, has been