STUDY AND IDENTIFICATION OF BACTERIA 



It is important to remember that such organisms 

 have very rarely been reported from pulmonary le- 

 sions, and when present they have been considered 

 as probably causative. 



The present view is that the finding of tubercle 

 bacilli in sputum has practically as great value as it 

 had before we knew of these various acid-fast bacteria. 



Tubercle Bacillus (Koch, 1882). This is 

 a rather long, narrow rod, 3X0.3^1. In the 

 human type it tends to show a beaded ap- 

 pearance, this not being due to spores, how* 

 ever. In the bovine type the staining is more 

 solid, the organism shorter and thicker, and 

 shows even a more scanty growth than human 

 T. B. It has been established that many of 

 the tuberculous affections of man, especially 

 those of the skin, bone, and mesenteric glands, 

 .are of the bovine type, while, as a rule, pul- 

 monary and laryngeal lesions are of the hu- 

 man type. Experiments by various com- 

 missions in different countries have shown 

 that human and bovine types are very closely 

 related and that not only may a bovine strain 

 affect man, but that human T. B. may infect 

 young calves. As bacilli of the bovine type 

 have frequently been reported in intestinal 

 and mesenteric tuberculosis of children it 

 shows the importance of sterilizing cows' 

 milk. Koch considered human infection from 

 bovine sources as of very rare occurrence. 



Although Kossel has found only two cases of 

 bovine T. B. in 709 cases of pulmonary tuberculosis 

 yet for the other types the findings are different. 

 Leaving out of consideration the frequency of in- 

 fections with bovine T. B. in children, recent sta- 

 tistics have shown that in adults about 4% of cervi- 

 cal adenitis, 22% of tabes mesenterica and 3. 5% of 

 bone and joint tuberculosis are due to bovine strains of T. B. 



Park and Krumweide, in a study of more than 1000 cases, found 

 about 10% due to bovine tuberculosis. Of 686 adult cases only 1.3% 



FIG. 26. Bacillus tuber- 

 culosis; glycerine agar-agar 

 culture, several months old. 

 (Curtis.) 



