CHAPTER XXVII 



BACILLI OF THE COLON-TYPHOID-DYSENTERY GROUP 



(Continued) 



THE BACILLUS OF TYPHOID FEVER 



(Bacillus typhosus, Bacillus typhi abdominalis) 



TYPHOID fever, because of its wide distribution and almost con- 

 stant presence in most communities, has from the earliest days been the 

 subject of much etiological inquiry. A definite conception as to its 

 infectiousness and transmission from case to case was formed as early 

 as 1856 by Budd. 1 



But it was not until 1880 that Eberth 2 discovered in the spleen and 

 mesenteric glands of typhoid- fever patients who had come to autopsy, 

 a bacillus which we now know to be the cause of the disease. Final 

 proof of such an etiological connection was then brought by Gaffky, 3 

 who not only saw the bacteria referred to by Eberth, but succeeded in 

 obtaining them in pure culture and studying their growth characteristics. 



Morphology and Staining. The typhoid bacillus is a short rod from 

 1-3.5 fj- in length with a varying width of from .5 to .8 n. In appear- 

 ance it has nothing absolutely distinctive which could serve to differen- 

 tiate it from other bacilli of the typhoid-colon group, except that it has 

 a general tendency to greater slenderness. Its ends are rounded without 

 ever being club-shaped. Contrary to the descriptions of the earliest 

 observers, typhoid bacilli do not form spores. They are actively motile 

 and have twelve or more flagella peripherally arranged. 



The bacilli stain readily with the usual anilin dyes. Stained by 

 Gram's method, they are decolorized. . 



Cultivation. Bacillus typhosus is easily cultivated upon the usual 

 laboratory media. It is not delicately susceptible to reaction, but will 

 grow well upon media moderately alkaline or acid. It is an aerobic and 

 facultative anaerobic organism, when the proper nutriment is present. 

 Upon agar plates growth appears within eighteen to twenty-four hours 



1 Budd, " Intestinal Fever," Lancet, 1856. 



2 Eberth, Virch. Archiv, 81, 1880, and 83, 1881. 



3 Gaffky, Mitt. a. d. kais. Gesundheitsamt, 2, 1884. 



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