362 THE DYSENTERY BACILLUS 



pigs against the inoculation of a fatal dose of bacilli and have powerful 

 agglutinating properties (1-10,000). Good results have also been obtained 

 in the treatment of human dysentery ; with Shiga's serum the mortality was 

 reduced two-thirds. The results with Martini and Lentz's goat serum and 

 with Krauss and Doerr's serum (prepared by sub-cutaneous inoculation of 

 living cultures) have not been so satisfactory. 



(ii) Gay, who repeated and confirmed Shiga and Kriise's experiments, 

 found that the agglutinating and prophylactic properties of dysentery- 

 immunized horse serum were more marked with the strain used for immuniza- 

 tion than with other strains. Independently of this Krauss and Doerr, 

 thinking that their experiments showed that a Shiga immune serum had no 

 action on bacilli of the Flexner type and conversely, recommended the pre- 

 paration of a mixed Shiga-Flexner serum which could be given indifferently 

 in all cases of dysentery whatever the infecting organism : acting on this 

 suggestion, Coyne and Auche prepared a polyvalent serum which has yielded 

 satisfactory results in the treatment of dysentery in man. Vaillard and 

 Dopter however affirm that a Shiga-serum gives as good results in a Flexner 

 as in a Shiga infection,, and in consequence consider that polyvalent serums 

 are unnecessary. 



(iii) To obtain a serum which was both anti-bacterial and antitoxic 

 Rosenthal immunized horses by inoculating them subcutaneously with 

 toxin (p. 361) and living cultures simultaneously. The serum is both prophy- 

 lactic and curative : it protects guinea-pigs in doses of 0*5 c.c., and in the 

 treatment of human dysentery very good results have been obtained, especially 

 by Korentchewsky in Manchuria where the mortality from dysentery fell 

 by more than one-half. 



(iv) Vaillard and Dopter, relying upon an observation by Besredka to the 

 effect that in the case of endotoxic organisms the most active antiserums are 

 obtained when the bacilli are inoculated directly into the blood-stream, im- 

 munized horses by inoculating living cultures and toxin directly into the 

 veins. 



The process of immunization must be carried out very slowly. Virulent cultures 

 of the Shiga bacillus were used and the toxin was prepared by Rosenthal' s method 

 (p. 361). Increasing doses of cultures were inoculated alternately with toxin, com- 

 mencing with 0'25 c.c., then 0'5. 1, 2, 3 c.c., rising to 50 c.c., an amount which was 

 never exceeded. The animals reacted violently (fever, prostration, temporary 

 paralysis of the hind limbs, loss of weight). The serum was collected a fortnight 

 to three weeks after' the last inoculation. 



Vaillard and Dopter's serum is both anti-bacterial and antitoxic. It pro- 

 tects rabbits when given in doses of 0*25-0'5 c.c., and leads to recovery 

 (doses of 1-2 c.c.) even when administered 24 hours after the experimental 

 infection In doses of 20-100 c.c. it is very efficient in the treatment of 

 human dysentery : the symptoms are alleviated almost at once, recovery is 

 rapid and the mortality lowered more than three-fourths. 



Vaccination in man. Shiga tried to vaccinate men by inoculating them with a 

 mixture of killed bacilli (80 parts) and serum (20 parts). The results were encourag- 

 ing, but the immunity is only of short duration. 



Immunity can be quickly produced by the inoculation of serum alone but does 

 not last long (10-12 days). 



In future experiments it would seem to be better to work with sensitized bacilli 

 according to the technique of Besredka : emulsions of bacilli are killed by heat 

 and agglutinated by a non-heated specific serum the excess of serum being removed 

 by repeated washing and centrifuging (p. 382). Such a vaccine is only slightly toxic : 

 in mice an immunity lasting 3-4 months is acquired in 4 days, and the susceptibility 

 of the animals is not increased during the process of immunization. 



