422 



THE PARATYPHOID BACILLI 



is separate and distinct from the aertrycke bacillus, and this observation has 

 been confirmed by Dean from a study of complement fixation reactions. 



Bainbridge has further shown that unless the absorption tests be applied the 

 paratyphoid B bacillus cannot be differentiated from the aertrycke bacillus, 

 and that in practically all cases the so-called paratyphoid B bacillus isolated 

 from cases of food-poisoning is in reality the aertrycke bacillus. The para- 

 typhoid B bacillus can however give rise to acute gastro-enteritis though this 

 would at present seem to be a very uncommon association (p. 432). 



Bainbridge's investigations have also demonstrated that a number of the 

 bacteria causing diseases in the lower animals (vide post) are not separate 

 species, but are either identical with the paratyphoid B bacillus, the 

 aertrycke bacillus or the gaertner bacillus, or are impure cultures of two or 

 more of these organisms. The various rat and mice viruses are therefore 

 shown by laboratory procedures, as well as by practical experience, not to 

 be so harmless to man and the domestic animals as they are claimed to be. 



Lignieres proposed to designate all those organisms which had the morpho- 

 logical and cultural attributes of the bacillus of hog-cholera [bacillus aertrycke} 

 by the name Salmonella after Salmon to whom the discovery of that organism 

 is due. This term has met with some acceptance on the Continent, and is a 

 convenient appellation under which to include a number of organisms very 

 closely related bacteriologically, though clinically the diseases to which they 

 give rise generally differ. It forms an appropriate classification for purposes 

 of practical bacteriology and will therefore be adopted here. The Salmonella 

 group, used in its original sense as defined above, includes the following 

 organisms : the bacillus paratyphosus B, bacillus enteritidis Aertrycke (syn. 

 bacillus suipestifer}, and bacillus enteritidis Gaertner : as well as a number 

 of organisms which have received specific names but which have now been 

 shown to be identical with one or other of the preceding : these are bacillus 

 danysz, bacillus typhi murium, bacillus psittacosis and bacillus icteroides. 



Other names also have been proposed for the group of organisms discussed 

 in this chapter : Theobald Smith suggested " the hog-cholera group " ; Durham, 

 the " intermediate group," and Trautmann, the "paratyphoid group." 



The paratyphoid A bacillus is obviously excluded on cultural grounds from 

 the Salmonella group. The "paratyphoid bacilli" will therefore be dealt with 

 under two headings (1) The bacillus paratyphosus A (2) The Salmonella group. 



The paratyphoid bacilli may then be grouped thus 



