PATHOGENIC BACTERIA. 



123 



similar to that of typhoid fever may be obtained with cultures 

 of colon bacilli. The colon bacillus is held responsible for most 

 of the complications of typhoid fever, such as peritonitis, 

 cholangitis, etc., by many writers. 



Staining. Ordinary stains; do not take Gram. 



Site. The bacillus has been found very constant in acute 

 peritonitis and in cholera nostras. Its presence in water would 

 indicate fecal contamination, as it is normally present in the 

 intestine. 



Points of Resemblance between Bacillus Typhi and Bacillus Coli 

 Communis. 1. Microscopic appearance; 2. Agar and gelatine 

 cultures ; 3. Sometimes growth on potato the same ; 4. Stain- 

 ing peculiarities ; 5. Resistance to carbolic acid. 



Points of Difference 



Colon Bacillus. 

 Less motile, 

 Gelatine colonies develop more 



rapidly, 

 Produces gas on dextrose or Does not, 



lactose media, 

 Coagulates milk, 

 Produces indol, 

 Growth on potato visible, 

 Changes neutral red to yellow. 



Typhoid Bacillus. 

 Actively motile, 

 Develop more slowly, 



Does not, 

 Does not, 

 Invisible, 

 Does not reduce neutral red. 



Differences are also noted in the growth on special media, 

 such as those of Hiss and Eisner. 



Varieties. By some bacteriologists the following bacilli are all 

 considered forms of the colon bacillus : B. lactis aerogenes of 

 Escherich, B. cavicida of Brieger, B. neapolitanus of Emmerich, 

 B. enteritidis of Gartner, and, together with some other allied 

 organisms, they are spoken of as the " colon group." 



