BEHAVIOR OF BACTERIOPHAGE IN DISEASE 



473 



with a negative blood culture, the temperature always falls during the following 

 days. 



Why is it that the filtrate from a blood which contains the bacteriophage fails 

 to cause a dissolution of the typhoid bacilli without further treatment? As a 

 matter of fact, experience shows that it may be necessary to make 2, 4, or even 6 

 passages before a complete dissolution of the typhoid bacillus will take place. 

 But, in these cases with a negative blood culture, the bacillus under test is the 

 organism of a stock laboratory strain, and it is not particularly astonishing that 

 the virulence of the bacteriophage may have to be enhanced before a macroscopic 

 effect can be observed. 



It is also pertinent to observe that the lysis which occurs is specific. That is, 

 it takes place only with B. typhosus and not with the related organisms B. coli 

 and B. dysenteriae Shiga. 



In brief, then, it is possible to find in negative blood cultures taken during the 

 later stages of typhoid fever a bacteriophage dissolving in a specific fashion the 

 typhoid bacilli of a laboratory stock culture. The lysis is not obtained by a 

 simple contact of the filtrate and the bacterium, but only after a few passages 

 with intervening filtrations. 



Cases with Positive Blood Cultures. 



In the table below are listed some of the cases which gave positive blood cul- 

 tures. The manner of testing the filtrates of the blood, and the organisms against 

 which they were tested, are the same as in the preceding group. 



Considering the data afforded by this group of cases it is obvious that in cases 

 yielding a positive blood culture, near the end of the septicemia a bacteriophage 

 may always be found which is able to dissolve the typhoid bacillus. 



At first sight, a result of this type would seem to be paradoxical. But let us 

 consider the facts in somewhat greater detail. The correlation of the available 

 data may permit us to understand and interpret such a situation. In the first 

 place, is there any relationship between the temperature of the patient, the posi- 

 tive blood culture, and the presence of the bacteriophage? 



Let us select from among our cases but one as an example, that of patient Go. 

 A and examine it from this point of view. 



