CHAPTER XX 



THE COLON TYPHOID GROUP 



(CONTINUED) 



B. TYPHOSUS. DYSENTERY GROUP 



B. Typhosus. In 1880 Eberth found the organisms now known 

 as B. typhosus in the spleen and diseased portions of the intes- 

 tines of persons who had died of typhoid fever. In 1884 Gaffky 

 obtained the organism in pure culture and was able to study its 

 growth characteristics. Its causal relationship to typhoid fever, 

 however, was particularly difficult to prove because, although 

 the organism was pathogenic for many animals when inoculated 

 subcutaneously or intravenously it was impossible to produce 

 infection by feeding and the characteristic symptoms of the disease 

 as they appear in man. Experiments with anthropoid apes, 

 increased knowledge concerning specific antibodies produced in 

 immune serum, the presence of the bacillus in the blood and feces 

 of typhoid patients and not in healthy persons other than " car- 

 riers " have been sufficient to establish the fact that B. typhosus 

 is the causal agent of typhoid fever. Recent work tends to show 

 that there are several strains slightly different culturally which 

 have hitherto been classified as B. typhosus, and that in the future 

 these organisms will be considered as the typhoid group rather 

 than the typhoid bacillus. 



Morphology and Staining. Typhoid bacilli are short rods 

 with rounded ends, varying from 1 /* to 3 /* in length and 0.5 

 to 0.8 7* in width. In hanging drop preparations they are seen 

 as single individuals or they remain attached and appear as threads. 

 Morphologically they are identical with B. coli save that they are 



208 



