DYSENTERY TOXIN. 83 



Dysentery toxin was first demonstrated by Conradi. Subse- 



Dysentery quently from experiments by Rosenthal, Todd, Kraus and 



Toxin. Doerr, etc., it became evident that this was a true toxin and not 



an endotoxin as was originally considered. Only the Kruse- 

 Shiga type of bacillus forms a toxin; for the Flexner kind, no definite toxin has 

 as yet been isolated. Recent investigators, however, especially Kraus and 

 Doerr are inclined to consider the human dysentery of the Kruse-Shiga 

 origin in the light of an intoxication or toxemia similar to diphtheria. The 

 lesions in the large intestine where the bacteria accumulate can be compared 

 to the diseased diphtheria tonsils, while the other manifestations, as the 

 central symptoms, cardiac disturbances, nervous sequelae, eye affections, 

 etc., can be taken as expressions of the toxemia. 



Like the other described toxins, the dysentery toxin can be obtained by filtration of 

 bouillon cultures. The meat infusion must be quite alkaline. The optimum alkalinity, 

 according to Doerr, is obtained by adding 0.3 per cent, soda to litmus neutral bouillon. 

 The precipitate thus formed which increases on sterilization should not be removed by 

 filtration. Doerr also advises finely powdered chalk (20 gm. pro liter) to be added to the 

 weakly alkaline bouillon before the last sterilization. The toxin is formed very gradually; 

 the maximum is derived after two to three weeks. The gray white pellicle upon the sur- 

 face of the culture can be taken as an indicator for the amount of toxin present. 



According to Kraus a good dysentery toxin can also be made by emulsifying the 

 bacteria (grown upon agar) in physiological salt solution and filtering this through Reichel 

 filters. 



The toxicity of individual strains of dysentery bacilli varies greatly. 



The strength of the toxin is diminished by heating for one to two hours at 60 C. 

 Higher temperatures destroy it, as 80 C. where destruction occurs in three minutes and 

 90 to 100 C. in one minute. 



Acids destroy the toxin probably by the formation of a non-poisonous compound. 

 The addition of a strong alkali restores the toxicity. 



Its preservation can be accomplished in a fluid state under the cover of toluol. 



The action of dysentery toxin can best be studied by its effect upon rab- 

 bits after intravenous inoculation. Large doses kill the animals in very 

 short time, six to seven hours. The ordinary lethal dose produces charac- 

 teristic symptoms consisting of paresis, diarrhea, which may be bloody, 

 paralysis of the bladder, hypothermia, etc. Death takes place in three to 

 four weeks. 



Given subcutaneously, or intraperitoneally, the toxin has only a very 

 mild action. The incubation period is especially prolonged. Given per os, 

 no effect is in evidence. 



Besides rabbits the other susceptible animals are monkeys, cats and dogs (to large 

 doses) ; chickens, pigeons and guinea-pigs are, in the opinion of Kraus and Doerr, not at 

 all affected by the toxin. 



The intestinal changes found at post-mortem examination of the animals very closely 

 simulate the pathological alterations occurring in man. A hemorrhagic necrotic enteritis 

 is present which in rabbits is regularly localized in the appendix and cecum, while in dogs 



