THE BACTERIOPHAGE IN DISEASE 183 



4. In all cases the fluctuations in the virulence, as well as the 

 fluctuations in the resistance of the bacteria, parallel the state 

 of the patient, and the onset of improvement coincides with the 

 moment when the virulence of the bacteriophage dominates 

 clearly the resistance of the bacterium. We thus see reproduced 

 in vivo the same mode of action as that observed in vitro; per- 

 manent and complete lysis, mixed cultures with negative trans- 

 fers, mixed cultures with alternations in the dominating force. 



In Indo-China an opportunity was afforded to follow four fatal 

 cases of bacillary dysentery in natives. At no time during the 

 course of the infection did the intestinal bacteriophage show a 

 trace of activity for the Shiga bacillus, either for the stock strain 

 or for that isolated from the stools of the patients. 



A last case offers an especial interest, for it shows that it is 

 not only in vitro that the bacteria are able to become refractory 

 to the action of the bacteriophage. Although this may occur 

 in vivo these cases must be very rare, even exceptional. 



Alix Desp. . . . (fifty-six years). The patient entered the 

 Pasteur Hospital on September 26, 1919. At the time of ad- 

 mission there was a profuse mucous diarrhea with thirty to forty 

 stools a day. Examination of the intestinal contents gave an 

 almost pure culture of a dysentery bacillus presenting atypical 

 characters, as follows: 



Non-motile bacillus. Gram negative. Indol positive. No black- 

 ening of lead acetate agar. No change in neutral red media. Litmus 

 sugar agar media not fermented with any of the sugars. In Barsiekow's 

 medium, maltose and lactose are unchanged, glucose and mannite are 

 turned red. After six transfers on agar it agglutinated to the titre (1 :6000) 

 with a Hiss agglutinating serum, to 1:400 with an anti-Flexner serum of 

 which the titre was 1:6000, and was not agglutinated at 1:20 by an anti- 

 Shiga serum. 



In spite of these atypical characters it is, then, a Hiss strain 

 possessing weak fermentative properties. 



When secured from the body this bacillus was not affected by 

 a bacteriophage very virulent for a normal Hiss bacillus, but it 



agar tubes and a portion is taken from these tubes for the tests conducted 

 during the course of the disease. It is well-known that resistance is 

 attenuated by successive transplantations. 



