CHAPTER IX 



" ACID-FAST " BACILLI 



TUBERCULOSIS LEPROSY THE SMEGMA BACILLUS- 

 GLANDERS 



11 Acid-fast " Bacilli 



AN important characteristic of the tubercle, leprosy, smegma, and 

 certain other bacilli is the property they possess when stained 

 with fuchsin of retaining the red colour after treatment with a 

 strong solution of a mineral acid (25 per cent, sulphuric or 30 per 

 cent, nitric). They are therefore termed " acid-fast." Most other 

 organisms are rapidly decolorised even by 1 or 2 per cent, sulphuric 

 acid, but it must be recognised that several apparently saprophytic 

 bacilli are also " acid-fast." The retention of the fuchsin colour in 

 spite of treatment with the acid seems to be due to the presence of 

 substances of a fatty or waxy nature within the organisms with which 

 the fuchsin either combines or is protected from the action of the acid. 



Moreover, by cultivating many saprophytic bacilli in media 

 containing butter, Bienstock and Gottstein converted them into 

 " acid -fast " forms. 



" Acid-fast " bacilli are also present in Johne's disease, occasion- 

 ally in rats, in butter (Petri, Rabinowitsch, Rubner), on certain 

 Graminaceae (the " Timothy -grass bacillus " of Moeller), and in 

 dung (the " Mist bacillus "). It has been suggested that these 

 saprophytic acid-fast bacilli may be derived from the tubercle 

 bacillus, but Panisset's work gives no confirmation of this. 



The StreptotricheaB occasionally exhibit " acid-fast " properties. 

 All the acid-fast bacilli seem to be Gram-positive. 



Tuberculosis 



Tuberculosis is, unfortunately, only too common in the 

 human subject, and most of the domestic animals and wild 

 animals in a state of captivity may be attacked by it. 



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