THE ANAEROBIC BACILLI 755 



a toxin in this way, Bengston of Hygienic Laboratory has been able 

 to prepare a B. Welchii antitoxin in which 1 c.c. of serum contains 

 one unit, one unit neutralizing 1000 M. L. D. of B. Welchii toxin. 16 



In laboratory animals infected with pure cultures of B. Welchii, 

 the antitoxin gives complete protection. Protection in laboratory 

 animals is also afforded by injections of antimicrobial sera prepared 

 by injections of whole broth culture of B. Welchii by Weinberg and 

 Seguin, but the antitoxin content of these sera has not been 

 determined. 



Bull and Pritchett in their original paper, state that the toxin 

 produced by B. Welchii is comparable to the toxins produced by 

 Tetanus and Diphtheria, and judged by its antigenic properties it 

 must certainly be classified as a true exotoxin. It differs from the 

 classical toxins in that toxin production varies directly with the 

 virulence of the strain and that it has no definite incubation period. 

 B. Welchii antitoxin cannot protect against mixed infections where 

 B. Welchii is associated with either Vibrion Septique or B. Oedema- 

 tiens. In this case the animal always dies of the Vibrion Septique 

 or B. oedematiens infection. However, since both these organisms 

 occur in a smaller percentage of cases and have rarely been isolated 

 from civilian cases of gas gangrene, B. Welchii antitoxin will prob- 

 ably prove of great value. 



Isolation. B. Welchii is a normal inhabitant of the intestinal 

 tract of adults and may be found in the stools of infants. Simonds 

 found B. Welchii present in eight out of nineteen stools of babies 

 under one year of age. It can be easily isolated from stools by 

 the following procedure: 5 c.c. of a fecal suspension in saline are 

 inoculated into a tube of milk which has been freshly boiled and 

 cooled. The tube is heated at 80 for one hour to kill off the 

 vegetative forms of the fecal flora, and is then incubated. The 

 development of the ''stormy fermentation" described above indi- 

 cates the presence of B. Welchii. Purification is best completed 

 by plating anaerobically from the milk culture. 



Animal inoculation is also useful in the isolation of B. Welchii. 

 The material suspected of containing B. Welchii is injected intra- 

 venously into a rabbit. After five minutes the rabbit is killed and 

 placed in the incubator for five to eight hours. At the end of this 

 time, the animal is usually distended with gas. At autopsy gas 



16 Bengston, Hygienic Laboratory Bulletin, No. 122, 1920. 



