THE GROUP OF THE DYSENTERY BACILLI 319 



Enzymes. Dysentery bacilli do not appear to produce extracellular 

 proteolytic enzymes. They do not liquefy gelatin, blood serum or 

 fibrin, and do not coagulate milk. Wells and Corper 1 have demon- 

 strated a lipase of moderate activity in the autolysates of dysentery 

 bacilli. 



Toxins. (a) Exotoxin. The nature of the poison produced by 

 the Shiga bacillus, the most virulent of the dysentery bacilli, is a 

 matter of debate. Todd, 2 Ludke, 3 Doerr, 4 and Kraus and Doerr 5 

 state that the organism produces a soluble (exo-) toxin which 

 stimulates antibody formation in suitable animals; the sera are 

 specifically antitoxic and protect laboratory animals against several 

 times the fatal dose of the toxin. According to Kraus and Doerr, 6 

 this toxin acts somewhat like that of the diphtheria bacillus; the 

 lesions observed in the large intestine are comparable to the lesions 

 of the diphtheria bacillus on the tonsils and pharynx. The nervous 

 lesions are somewhat like those of poliomyelitis. Intravenous injec- 

 tion of large doses in rabbits causes death in from six to eight hours; 

 smaller doses cause paresis, diarrhea, which is frequently bloody, 

 paralysis of the bladder, hypothermia and death in one to four weeks. 

 Postmortem there is a mucohemorrhagic enteritis, usually localized 

 in the cecum. It is stated that the entire intestinal tract is involved 

 in dogs, with the duodenum particularly affected. Intraperitoneal 

 and subcutaneous injections give a much milder reaction with a pro- 

 longed incubation period. The toxin is inactivated by acids, but its 

 potency may be partially restored when the acid is neutralized with 

 alkali. Conradi 7 and others find dead cultures almost as toxic as the 

 living bacilli ; they call attention to the toxic properties of autolysates 

 (in sterile water) of the Shiga bacillus, a fact which was pointed out 

 by Gay 8 some time before. It is probable that both soluble and 

 autolytic poisons are concerned in the toxicity of filtrates of broth 

 cultures of the organism. The toxic substances may be obtained in 

 dry form by saturating the broth (freed from bacilli by filtration 

 through unglazed porcelain) with ammonium sulphate, dialyzing the 

 precipitate to remove the ammonium salts, and evaporation of the 



1 Jour. Infec. Dis., 1912, xi, 388. 



2 Brit. Med. Jour., December 5, 1902, ii; October 4, 1903, ii. 



3 Jour. Path, and Bact., 1905, x, 328. 



4 Cent. f. Bakt., Orig., 1905, xxxviii, 420, 511. 

 s Ztschr. f. Hyg., 1906, Iv, 1. 



6 Loc. cit. 



7 Deutsch. med. Wchnschr., 1903, xxix, 26. 

 sPenna. Med. Bull., 1902. 



