BACTERIA SUSCEPTIBLE TO BACTERIOPHAGY 245 



At different times I have isolated these unidentified bacilli and I have 

 always found that at the time of the disappearance of the more or less 

 severe disturbance, the stools contained a bacteriophage virulent for the 

 bacillus isolated from the intestinal tract at the beginning of the dis- 

 ease. Generally these bacteriophages are also virulent for the typical 

 dysentery types, but the reciprocal of this is not always true, for the 

 bacilli may often be insusceptible to the action of bacteriophages having 

 a maximum virulence for B. dysenteriae. 



During the summer of 1919, I studied about 100 cases of diarrhea in 

 infants on the service of Dr. Hutinel at the Hopital des Enfants-malades. 

 With the exception of the cases which progressed rapidly and died 

 (cases to which we will return) I constantly isolated from the stools a 

 bacillus which I have also found in a few cases of gastro-enteritis in 

 adults. This organism I have termed B. dysenteriae X.^^i 



When inoculated on litmus sugar agar media it fails to ferment any 

 of the sugars tested (lactose, glucose, levulose, saccharose, maltose, 

 mannite, galactose). It causes no change in lactose and maltose 

 Barsiekow medium, but this medium containing glucose and mannite 

 is turned red. It is agglutinated by convalescent serum in titres of 

 1:100 to 1:500, is not agglutinated by anti-Flexner or anti-Shiga sera. 

 With a serum which agglutinates the Hiss strain to 1:2500 the "X" 

 strain is agglutinated in dilutions of 1 : 200. It is non-motile, is morpho- 

 logically like the other dysentery organisms, is Gram-negative, and is 

 toxic for rabbits. 



Several races of bacteriophage active for this bacillus have been 

 isolated. This bacteriophage is constantly present in the intestine 

 in convalescents who have shown B. dysenteriae "X." in their stools 

 during the infection. Races have also been recovered from the intestinal 

 tracts of healthy animals, both man and other animals. The "X" 

 bacillus constitutes a homogeneous species as regards the bacteriophage. 



Certain races of the bacteriophage active for B. dysenteriae "X" 

 were likewise active for other species of dysentery bacilli, others were 

 virulent for only one or two among them. When maintained for several 

 generations at the expense of B. dysenteriae "X" they almost completely 

 lose their activity for other dysentery organisms (d'Herelle^^O • 



5. Bacilli associated with fowl typhoid (Eberthella sanguinaria, pfaffi,, 

 Rettgeri, Jeffersonii, Salmonella pullora) 



Eherthella sanguinaria is a very homogeneous species. During the 

 course of the epizootic in France occurring most extensively during the 



