312 



BACILLUS OF MALIGNANT (EDEMA. 



Fio. 139. 



germ. It is decolorized by the Gram method, but stains well 



with the anilin dyes. 



The bacillus of malignant oedema is easily obtained from 

 the oedematous tissues of animals suffering 

 with the disease, or from contaminated gar- 

 den earth. The bacillus of tetanus is fre- 

 quently associated with it. It is an obliga- 

 tive anaerobe. 



The colonies usually develop in the depth 

 of the medium, and are solid-looking masses, 

 white in color. The colonies have a very 

 irregular edge like those of the hay or potato 

 bacilli, and appear to be filled with a mass of 

 threads (Fig. 139). Gelatin is liquefied. In 

 glucose-gelatin gas is evolved, and there is a 

 distinct odor. Blood-serum is usually rapidly 

 liquefied. Bouillon is rendered turbid, with 

 the formation of CO 2 and hydrogen. 



The organism is invariably present in pu- 

 trefactive processes, in garden earth, in manure, 

 and. in dust, and is always associated with the 

 tetanus bacillus and several saprophy tic germs. 

 Only a very few cases of malignant oedema 

 have been reported as occurring in man. As 

 in the case of the tetanus bacillus, a penetrat- 

 ing wound is necessary before infection will 

 occur. In fact, the same conditions which 

 obtain in infection with the tetanus bacillus 

 also hold good in infection with the bacillus 

 of malignant oedema. Animals are readily 

 immunized to infection. 



Bacillus aerogenes capsulatus : This organ- 

 ism was discovered by Welch in the blood- 

 vessels of a patient suffering with an aortic 

 aneurism. It is a straight or slightly curved 

 rod, of variable length and thickness, with 



either rounded or squared ends. It is encapsulated and forms 



long chains of filaments. It is non-motile and does not form 



spores. 



Colonies of the ba- 

 cillus of malignant 

 oedema in deep gel- 

 atin culture. (After 

 Fraenkel and Pfeif- 

 fer.) 



