760 PATHOGENIC MICROORGANISMS 



common sugars, 27 and forms a loose clot in milk in three or four 

 days. It liquefies gelatin, but does not attack coagulated serum. 



PATHOGENICITY. B. oedematiens is usually pathogenic, although 

 Weinberg and Seguin report the isolation of two non-virulent strains, 

 rabbits are less susceptible than guinea-pigs. Mice are also sus- 

 ceptible. It may or may not enter the blood stream. The lesion 

 in the animal is characterized by a whitish gelatinous exudate and 

 the absence of gas. The* production of agglutinating sera with B. 

 oedematiens has not been satisfactory, because B. oedematiens tends 

 to agglutinate spontaneously. It is feebly hemolytic much less so 

 than vibrion septique and B. perfringens. 



TOXIN. B. oedematiens forms a soluble toxin. Different strains 

 vary in their toxin production. With a potent strain 1/100 c.c. of 

 toxin injected intravenously kills a 300-400-gram guinea-pig in 

 forty-eight hours. This toxin differs from those of vibrion septique 

 and B. Welchii in that it never kills acutely on intravenous injection. 

 The toxin is prepared according to Weinberg and Seguin, by grow- 

 ing B. oedematiens in broth containing chopped veal for six to ten 

 days. 



ANTITOXIN. Rabbits, sheep and horses have been used to produce 

 antitoxic sera. Immunization is difficult and small doses must be 

 used at first. Weinberg and Seguin prepared an antitoxin in a horse 

 of such a titer that 1/10,000 dilution neutralized two lethal doses 

 (guinea-pig). 



B. Fallax. B. fallax was discovered during the war by Wein- 

 berg and Seguin. It is a much less important factor in gas gangrene 

 than the members of the saccharolytic group already described. It 

 is. usually associated with other pathogenic anaerobes. Weinberg 

 and Seguin cite one case in which it invaded the blood stream and 

 caused death. It was isolated by Henry in three cases out of a series 

 of fifty. 



It is an anaerobic Gram-positive bacillus, resembling vibrion 

 septique in appearance. It has a capsule and is slightly motile. It 

 does not form spores readily in most culture media. Spores are 

 formed on coagulated serum and are subterminal. 



B. fallax coagulates milk very slowly. It does not liquefy gelatin 

 or coagulated serum. 



B. fallax is not hemolytic. It is only slightly pathogenic and 

 soon becomes avirulent on artificial cultivation. 



27 Wolf, Jour. Pathol. and Bacter., 23, 1920, 254. 



