198 THE BACTERIOPHAGE 



4. Typhoid fever of extreme severity 



1. Andr6e Dess. . . . (thirty years, fig. 13). 



2. Jeanne Cot. . . . (twenty-four years, fig. 14). 



In these two cases strains of B. typhosus were isolated at different 

 times during the course of the disease. These bacilli presented 

 a marked resistance to the action of a very active strain of anti- 

 typhoid bacteriophage and lost this resistance only after about 

 ten transfers on agar. It is to be noted that at their isolation 

 from the organism these bacilli were inagglutinable (this fact 

 has frequently been observed) and that they did not become 

 agglutinable until after a series of cultures. This transitory 

 inagglutinability is, as we have seen, associated with resistance 

 to the action of the bacteriophage. 



Examination of the curves shows clearly the struggle which 

 was carried on within the organism between the bacterium and 

 the bacteriophage, and the repercussions of this campaign upon 

 the state of the patient. 



We find then, in typhoid fever, — an intestinal infection compli- 

 cated by a septicemia — the same facts as seen in bacillary 

 dysentery. 



The virulence of the bacteriophagous ultramicrobe isolated 

 from the stools of the typhoid patient is not limited, in general, 

 to a single pathogenic bacillus; at one and the same time it ex- 

 tends, in some degree, to some or all of the bacilli of the colon- 

 typhoid-dysentery group. This fact is particularly noted in 

 mild cases or those of average severity. In the severe cases the 

 bactericidal action is more specific and is often limited to the 

 specific pathogenic organism and to B. coli, the latter always 

 being attacked. In certain very severe cases the specificity 

 becomes such that up to the beginning of actual improvement 

 only the bacillus isolated from the patient is attacked, whether 

 it has been secured by stool or by blood culture, to the exclusion 

 of other bacilli, taken either from old laboratory cultures or from 

 strains recently isolated from other patients. It seems, then, 

 that in the course of their struggle each of the two organisms 

 present, — bacteriophage and bacterium — acquires an individual 

 personality, which differentiates them from other organisms of 



