Etiology. Pathogenicity. 



33 



Etiology. The bacillus oedematis maligni, Koch, (Vibrion 

 septique, Pasteur) is an anaerobic bacterium resembling the 

 anthrax bacillus, but appearing somewhat more slender, rod- 

 shaped, peritrically flagellated, motile and multiplying by fission 

 and spore formation. (Figs. 8 to 10.) Several rods unite to 

 form longer chains in which the ends in contact with each other, 

 as well as the free ends, appear rounded. In artificial media, 

 as well as inside the animal body after death, the bacilli grow 

 to long, curved unsegmented threads. In the bacilli, oval spores 

 develop either in the middle or ends (exceptionally even the 

 edematous fluid taken from the living animal contains spore- 

 bearing bacilli [Jensen & Sand]). 



Staining. With aqueous aniline dyes the bacilli stain readily, aud 

 they also take the Gram stain after being carefully 

 treated with alcohol. 



Cultivation. The cultivation of this organism is 

 only possible under oxygen-free conditions. Stab 

 cultures in agar or gelatin show along the stab cloudy 

 or lentil-shaped colonies which usually develop at the 

 bottom of the medium and close to which the gelatin 

 is later liquefied. In coagulated blood serum and also 

 in dextrose bouillon (not in saccharose and lactose, 

 Smith) gas having a characteristic sweetish putrid 

 odor is formed, which later causes disruption of the 

 media. (Fig. 11.) Kerry found in the gases hydro- 

 gen, hydrogen sulphide, carbon dioxide and methane. ^1 

 Milk is changed in a few days into a watery fluid with 

 gas formation and the collection of a layer of fat on 

 the surface (Smith). In bouillon cultures the bac- 

 teria produce toxins in small quantities (Roux and 

 Chamberland). 



The spores show great vitality. Dry muscle substance 

 and spore-containing edema fluid enclosed in glass tubes prove 

 virulent even after years. In fluid media spores are destroyea 

 after heating to 100°C. for fifteen minutes (Sanfelice), wliile 

 in the dry state they are killed in ten minutes at 120°C. 

 (Arloing). Direct sunlight kills them only slowly. Disin- 

 fectants are only effective in strong solutions and after pro- 

 longed contact. Sporeless bacilli are quickly destroyed in the ^^^^^_ 

 presence of air and sunlight as well as by putrefaction. i ^^^^^^ J 



Fig. 11. Stab cul- 

 ture of edema ba- 

 cillus in dextrose 

 agar. 



Pathogenicity. After the inoculation of a 

 pure culture in the depth of the connective tis- 

 sue, a rapidly extending swelling develops at 

 the point of injection. It becomes crepitating as 

 a result of gas formation within, and the animal soon dies of a 

 form of septicemia. Guinea pigs and mice succumb in from 

 24 to 28 hours. Cattle can be infected only with great difficulty, 

 and feeding of spore-containing material will not produce the 

 disease even in susceptible animals. Edema bacilli injected 

 into the blood produce the disease only when they find a suita- 

 ble soil for their development somewhere in necrotic tissue (for 

 instance, in previously ligated testicles [Chauveau]). 



