33 



TYPHOID FEVER. 



It has consequently become common to speak of the 

 typhoid group and the coli group in order that such 

 varieties may be included. In the coli group cases may 

 be met with which do not give an indol reaction, which 

 do not curdle milk, or which do not produce gas, and 

 Gordon even includes varieties producing alkali, or slowly 

 liquefying gelatine. Two of the most important varieties, 

 the bacillus enteritidis (Gaertner) and the bacillus of psitta- 

 cosis, are described below. 



METHODS OF THE DIAGNOSIS OF THE TYPHOID BACILLUS. 



The Differences between the B. typhosus and the 

 B. coli : 



B. Typhosus. 



Flagella more numerous, longer, 



and more wavy. 



In artificial media growth gener- 

 ally slower and not so vigorous. 

 Growth on fresh acid potatoes, a 



nearly transparent film. 

 Very slight acid production 



in ordinary media, followed 



sometimes by production of 



alkali. 

 Fermentation of lactose very 



slight if any. 

 Milk not coagulated. 

 Gelatine shake cultures no gas 



formation. 

 Production of indol in ordinary 



bouillon nil. 

 Agglutination. Bacilli become 



clumped together and motion- 

 less in the serum of a typhoid 



patient. (A similar reaction is 



given by the blood serum of an 



animal immunised against the 



typhoid bacillus.) 



Bacillus Enteritidis (Gaertner). In 1888 Gaertner, in investi- 

 gating a number of cases of illness resulting from eating the flesh of a 



B. Coli. 

 Flagella fewer and shorter. 



Growth faster and more vigorous. 



Growth on potatoes, a brownish 



pellicle. 

 Well-marked acid production. 



Fermentation pronounced. 



Milk coagulated. 



Abundant gas formation round 



colonies. 

 Well-marked indol production. 



In most cases the bacilli remain 

 actively motile, but sometimes 

 clumping occurs. 



