513 



O'/i a New Factor in the Mechanism of Bacterial Infection. 

 By W. E. Bullock and W. CRAiiEE. 



(Communicated by Prof. W. Bullocli, F.R.S. Received January 14, 1919.) 



(Prom the Laboratories of the Imperial Cancer Eesearch Fund.) 



Introduction. 



The observations recorded in this paper were made in the course of 

 investigations on gas gangrene. The work of Mcintosh, of Weinberg and 

 S^guin, and of other investigators has shown tliat the organisms chiefly 

 responsible for the production of gas gangrene are the bacillus of Welch, the 

 Vibrion septique, and the Bacillus oedematiens. Small amounts of broth 

 cultures of these organisms when injected into animals belonging to a 

 susceptible species, e.g., the mouse or the guinea-pig, produce a violent gas 

 gangrene, and kill the animal within 24 hours. 



It is known and was confirmed by us that suspensions in saline of 

 B. Welchii and of Vibrion septique. from a surface culture are practically 

 non-pathogenic ; half a cubic centimetre of a dense suspension of these 

 organisms can be injected into a mouse or guinea-pig subcutaneously or 

 intramuscularly without producing gas gangrene and, indeed, without 

 producing any signs of ill-health. The same result is obtained if broth 

 cultures of B. Welchii or of Vibrion septique, which contain toxins in 

 addition to the bacteria, are centrifuged, and the bacteria, after having been 

 washed free from adherent toxin, are suspended in saline and injected. In 

 the case of B. osdematiens, the toxin is so potent that it is not easy to 

 remove the last traces of toxin by washing, and it is necessary to destroy the 

 last traces of toxin by heating the washed bacteria to 80° C. for half-an-hour, 

 when spores are formed. These spores, when suspended in saline and 

 injected, are again non-pathogenic. Very occasionally it does happen that 

 gas gangrene develops after the injection of detoxicated bacteria or their 

 spores, but such an event is qidte exceptional and apparently accidental. 

 With the detoxicated B. Welchii, for instance, we have observed gas gangrene 

 to occur only once out of a large number of experiments on more than a 

 himdred animals. But if these " detoxicated " bacteria or spores are again 

 mixed with a dose of toxin too small to produce an effect by itself, gas 

 gangrene develops regularly and kills the animal. 



Further investigations, which will be published separately, showed that 

 the bulk of the detoxicated bacteria when injected undergoes lysis, while 



