ACID-FAST BACILLI 371 



ACID-FAST BACILLI. 



When discussing the morphology of the tubercle bacillus it was 

 pointed out that it has peculiar staining properties. While it is 

 difficult to induce the organism to take up watery solutions of basic 

 anilin stains it is equally difficult to decolorize it after the dye has 

 once penetrated into the substance of the bacillus. The reason for 

 this action is that the tubercle bacillus possesses a form of membrane 

 composed of a waxy material. A few other bacilli act toward stains 

 more or less like the tubercle bacillus and are known under the 

 common name of acid-fast bacilli. Several have been found living 

 in the outside world, evidently as harmless saprophytes. 



Moeller has discovered and described three varieties of such bacilli. 

 One he found on timothy grass (Phleum arvense), another in manure, 

 and a third in plant dust in barns. The three varieties are easily 

 raised on artificial culture media, on which they grow rapidly, forming 

 on the third or fourth day a yellowish to dark orange pigment. The 

 bacilli are even more firmly acid-proof than the tubercle bacilli, and 

 can still better withstand dipping in dilute mineral acids and washing 

 in alcohol. The first two varieties of Moeller's acid-fast bacilli grow 

 best at temperatures of 45 to 50 C.; when obtained from young 

 cultures they show some motility in the hanging drop, while older 

 cultures display considerable pleomorphism with branching forms. 



Moeller's grass bacillus when inoculated intraperitoneally into 

 guinea-pigs leads to pseudotubercular lesions'- and the formation of 

 abscesses containing a purulent or somewhat caseous material. 

 Typical tubercles with giant and epithelioid cells are, however, not 

 formed. Moeller also obtained an acid-fast bacillus from a nodule 

 of a steer; it grew very rapidly at room temperature, and in intra- 

 peritoneal inoculation produced a pseudotuberculosis in guinea-pigs. 



Petri and Rabinowitsch have isolated from butter, acid-fast bacilli 

 which closely resemble the acid-fast bacilli of Moeller. Petri found 

 such bacilli 54 times in 102 specimens of butter examined; Rabin- 

 owitsch 23 times in 80 specimens examined; Klein in London in 8 out 

 of 100 specimens, and Santori in Rome in all specimens of butter 

 tested for the presence of such organisms. The Petri-Rabinowitsch 

 bacilli are not as firmly acid-fast as the tubercle bacillus. When 

 raised on agar they form a thick, cream-like growth, which later 

 assumes an orange color, then shrivels and becomes cracked and 

 uneven. If repeatedly passed through animals the growth becomes 

 dry and cracked, and closely resembles a culture of tubercle bacilli 

 on glycerin agar. Bouillon cultures of the Petri-Rabinowitsch acid- 

 fast bacilli remain clear and become covered with a thick folded 

 membrane which gives off a disagreeable ammoniacal odor and forms 

 a small amount of indol. If these butter bacilli are inoculated intra- 

 peritoneally into guinea-pigs they produce pseudotubercular lesions. 



