BACILLUS (EDEMATIS MALIGNI 495 



Resistance to Physical Agents. The vegetative cells are not resistant 

 to heat, three to five minutes' exposure to 60 C. killing them. The 

 spores are very resistant to drying and heating; an exposure to 80 

 C. for several hours is necessary to kill them, and from thirty to 

 sixty minutes' exposure to 90 C. Sunlight will not kill the organisms 

 even after several days' exposure, and in the dark the spores may 

 remain alive for many years. 1 



Products of Growth. B. oedematis maligni forms a gelatinase, case- 

 ase, and apparently a non-specific proteolytic ferment as well. The 

 disagreeable odor noticed in protein media is due to indol, hydrogen 

 sulphide and probably mercaptans. Acid, chiefly butyric and lactic, 

 and gas, probably carbon dioxide and hydrogen, are produced in 

 dextrose broth. 



Toxin. It has been claimed that the bacillus of malignant edema 

 produces a soluble toxin. It is found that these organisms grown 

 anaerobically in plain broth for several days do develop a slight 

 toxicity, which can be demonstrated by filtering the broth through 

 sterile unglazed porcelain filters and injecting several cubic centi- 

 meters of the filtrate into guinea-pigs; they die after a longer or 

 shorter time. It is also claimed that the organism produces a leuko- 

 cidin which destroys leukocytes. 



Pathogenesis. The virulence of cultures of the malignant edema 

 bacillus varies very considerably. Infection rarely or never occurs in 

 man. Brieger and Ehrlich 2 have reported two cases of typhoid fever 

 which terminated fatally after an invasion by an organism morphologi- 

 cally like the malignant edema bacillus, which produced rather exten- 

 sive edema in the tissues. It is quite possible that this organism was 

 in reality, however, the gas bacillus. In small laboratory animals, 

 as rabbits and guinea-pigs, the organism typically produces a rapidly 

 fatal septicemia with considerable edema at the site of injection. 

 In larger animals, horses, cattle, sheep and swine, the edema is more 

 pronounced, as Koch 3 pointed out, and the organism tends to remain 

 localized at the site of inoculation. As a rule there is no general sep- 

 ticemia. In wound infections with this organism the incubation period 

 is from one to two days. Infection only takes place in deep or con- 

 tused wounds where oxygen is absent. 



Like the tetanus bacillus, the spores of the malignant edema bacilli, 

 freed from adherent culture media or other organisms, do not as a 



1 von Sz&kely, Ztschr. f. Hyg., 1903, xliv, 363. 



2 Berl. klin. Wchnschr., 1882, No. 44. s Loc . c i t . 



