7 8 



STUDY AND IDENTIFICATION OF BACTERIA 



3. In various excretions of animals, as in 

 dung, urine, etc. 



4. Normally in man from skin, nasal 

 mucus, cerumen, and tonsillar exudate. 



It is important to remember that such organisms 

 have very rarely been reported from pulmonary 

 lesions, 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;*. In the 

 human type it tends to show a beaded appear- 

 ance, this not being due to spores, however. 

 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, pulmo- 

 nary and laryngeal lesions are of the human 

 type. Experiments by various commissions 

 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 considers human infection from bovine 

 sources as of very rare occurrence. 



FIG. 25. Bacillus tuber- 

 culosis; glycerine agar-agar 

 culture, several months old. 

 (Curtis.) 



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 infections with 



bovine T. B. in children, recent statistics have shown that in adults about 4% of 

 cervical adenitis, 22% of tabes mesenterica and 3.5% of bone and joint tuberculosis 

 are due to bovine strains of T. B. 



