44 BACTERIOLOGY 



BACILLI 



Bacillus Tuberculosis. The discovery of the tubercle 

 bacillus by Koch in 1882 may almost be said to mark an 

 epoch in the history of medicine. It is a slender rod- 

 shaped anaerobic germ found in the sputum, pus, and 

 tissues of tuberculous lesions. It is pathogenic to man, 

 apes, cows, sheep, horses, rabbits, guinea-pigs, and field 

 mice. Goats and dogs are immune. 



Infection occurs through the nasopharynx, lungs, and 

 gastro-intestinal canal. Particles of dried sputum may 

 be inhaled and infection take place in the lungs, the 

 most frequent location of the trouble, or they may be 

 ingested with the food, and infection take place through 

 the tonsils or neighboring lymph-glands, or through 

 the intestinal mucosa, especially in infants. 



Entering the blood through the intestinal mucosa, 

 they may become located in most any of the organs of 

 the body. The most frequent locations being the lungs, 

 lymph-nodes, bones, intestines, skin, meninges, perito- 

 neum and pleura, testicles, ovaries, kidneys. Milk is, 

 no doubt, a frequent source of infection, becoming con- 

 taminated in handling. At present there is some ques- 

 tion of the transmissibility of bovine tuberculosis to 

 humans, Koch having claimed it to be a negligible factor, 

 while others look upon it as a frequent source of infec- 

 tion, especially in children. Cattle may be infected 

 with the human variety, but it is manifestly impossible 



