CHAPTER XXX 



ACID-FAST GROUP 



THE Bacillus tuberculosis, B. kprce, the bacillus of Johnes' 

 disease, and certain common non-pathogenic bacteria isolated 

 from hay, dung, milk, butter, and other sources, have common 

 morphological and staining characters which associate them as the 

 acid-fast group. The crucial test for these forms is their ability 

 to retain stains when treated with strong acids. They do not 

 stain readily with the common anilin dyes, but when once stained 

 they are " acid-fast." Hot carbol-fuchsin is commonly used in 

 determining this character. 



The members of the acid-fast group of bacteria are all slender, 

 non-motile rods, without capsules or spores, gram-positive, and 

 acid-fast. Slight variations in morphology and cultural characters 

 and considerable differences in pathogenesis serve to differentiate 

 the various species. All the species may occasionally produce 

 branched cells and threads, and it has been concluded by some in- 

 vestigators that they belong rather with the fungi, or at least with 

 the higher bacteria than with the lower bacteria. 



Care should be used not to confuse the term pseudotuberculosis, 

 and particularly the bacteria associated with that disease, with the 

 true tubercle bacilli and related forms. As has before been stated, 

 the term pseudotuberculosis is purely pathological, and refers to 

 the type of lesions produced in the body, and not to any resemblance 

 of the organisms causing the disease to those of tuberculosis. 

 The pseudotubercle bacilli are more closely related to the diph- 

 theria group, and have already been discussed. 



Bacillus tuberculosis 



Synonyms. Bacterium tuberculosis; Mycobacterium tubercu- 

 losis. 



Disease Produced. Tuberculosis in mammals and birds. 

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