310 BACTERIA PATHOGENIC TO MAN 



Bird (Avian) Tuberculosis. Tuberculosis is very common and infec- 

 tious among fowls. The bacilli themselves grow more readily on 

 artificial culture media and produce a more even and moist growth. 

 They are able to develop at a temperature of 43.5 C., which is above 

 that at which the human and bovine types can usually grow. The 

 bacilli are more apt to show branching forms than the human. In 

 rabbits they produce very similar lesions, but guinea-pigs are much 

 less susceptible. Birds are much less susceptible to bacilli from human 

 or bovine sources than to those from birds. Nocard states that bacilli 

 from human sources placed in collodion sacs and inserted into the peri- 

 toneal cavity of birds gradually acquire avarian characteristics, so that 

 after eighteen months they can readily infect fowls and approach the 

 avian cultural type. This suggests that bovine bacilli remaining in 

 man for years might acquire human-type characteristics. They are 

 undoubtedly from the same stock as the mammalian varieties, but have 

 become modified; it is not believed that they are any factor in the 

 production of human tuberculosis. 



Tuberculosis in Fish. In certain species of fish a tuberculous disease 

 has been noted. The bacilli have the staining characteristics of the 

 warm-blooded types, but do not grow at body temperature and do 

 not affect mammals. 



Methods of Examination for Tubercle Bacilli and Other Associated 



Bacteria. 



One of the most important results of the discovery of the tubercle 

 bacillus relates to the practical diagnosis of tuberculosis. The staining 

 peculiarities of this bacillus renders it possible by the bacteriological 

 examination of microscopic preparations to make an almost abso- 

 lutely positive diagnosis in the majority of cases. A still more certain 

 test in doubtful cases is the subcutaneous or intraperitoneal injection 

 of guinea-pigs, which permits of the determination of the presence of 

 numbers of bacilli, so small as to escape detection by microscopic 

 examination. For the animal test, however, time is required at least 

 three weeks, and, when the result is negative, at least six weeks before 

 any positive conclusion can be reached, for when only a few bacilli are 

 present tuberculosis develops slowly in animals. 



Microscopic Examination of Sputum for the Presence of Tubercle Bacilli. 

 1. COLLECTION OF MATERIAL. The sputum should be collected in a 

 clean bottle (two ounce) with a wide mouth and a water-tight stopper, 

 and the bottle labelled with the name of the patient or with some other 

 distinguishing mark. The expectoration discharged in the morning is 

 to be preferred, especially in recent cases, and the material should be 

 coughed up from the lungs. Care should be taken that the contents 

 of the stomach, nasopharyngeal mucus, etc., are not discharged during 

 the act of expectoration and collected instead of pulmonary sputum. 

 If the expectoration be scanty the entire amount discharged in twenty- 

 four hours should be collected. In pulmonary tuberculosis the puru- 



