444 THE SALMONELLA GROUP 



SECTION IV. ISOLATION AND IDENTIFICATION OF THE 

 BACILLUS. 



The distribution of the bacillus in the bodies of infected persons and 

 animals is the same as in the case of the aertrycke bacillus. 



In attempting the isolation of the gaertner bacillus from material suspected 

 to contain it the same methods will be adopted as in the case of other mem- 

 bers of the group. After preliminary enrichment in dulcite peptone water 

 the culture will be plated on Conradi-Drigalski's or MacConkey's medium and a 

 number of colourless colonies picked oil and tested as regards their fermenta- 

 tion reactions. If these reactions are in agreement with those of the gaertner 

 bacillus the bacilli must be tested against a known gaertner serum. Absorp- 

 tion tests are unnecessary in this case because the agglutination reaction is 

 quite definite. 



4. P8EUDO-GAERTNER BACILLI. 



This term has been adopted by Savage to describe certain organisms not uncom- 

 monly found in food and in the animal intestine and not infrequently present also in 

 the human intestine. 



These organisms resemble the Salmonella group of bacilli so closely as to be, 

 culturally and biochemically, almost indistinguishable from them : they differ 

 from them however in not being agglutinated by specific Salmonella serums. It 

 follows from this that pseudo-paratyphoid B or pseudo-aertrycke bacilli would be 

 ai> equally 'correct designation. 



It would seem probable that Savage's pseudo-gaertner bacilli may be the same 

 as the organisms referred to by German observers as paratyphoid C bacilli. 



There remain for description three organisms discovered by various observers 

 in fatal diseases in mice, rats and parrots respectively and known as Bacillus 

 typhi murium. Danysz's virus and Bacillus psittacosis. They have now been 

 shown to be identical either with the aertrycke, gaertner or paratyphoid 

 B bacilli. The precise relationships of a fourth, Bacillus icteroides, have not 

 yet been worked out. 



5. BACILLUS TYPHI MURIUM. 



Lceffler applied the above description to an organism which was the infecting 

 agent in a fatal epizootic among the mice in his laboratory. 



The organism is pathogenic to mice (Mus musculus) and field mice (Mus arvicola). 

 Loser investigated a similar epizootic among M us agrarius : Merechowsky and 

 Issatchenko have also described similar epizootics, in one case affecting ground- 

 squirrels, in the other white rats. Danysz recovered Lceffler's bacillus in an epizootic 

 among M us arvicola. 



Trommsdorf, whose observations have been confirmed by Mayer and Bonhoff and 

 by Shibayama, has shown that Loemer's bacillus may infect man. 



Bonhoff gave reasons for including Lceffler's bacillus with the gaertner bacillus 

 and the aertrycke bacillus in the paratyphoid group. 



Bainbridge has examined four strains of the bacillus typhi murium including one 

 from Lceffler and finds that the name is applied to different organisms or to impure 

 cultures of organisms, thus : two strains of the so-called bacillus typhi murium were 

 cultures of the gaertner bacillus, a third was a mixture of the gaertner bacillus and 

 the aertrycke bacillus and a fourth a mixture of the aertrycke bacillus and the 

 paratyphoid B. bacillus. 



6. DANYSZ'S VIRUS. 



From a study of the cultural, agglutination and absorption reactions of a virus 

 obtained from an epizootic among mice and known as " Danysz's virus," Bain- 

 bridge has shown that it is a pure culture of the bacillus enteritidis Gaertner. 



