DETECTION OF THE BACILLUS 339 



A. Sputum. 



1. Microscopical examination. The search for tubercle bacilli in sputum 

 is easy when the latter is purulent and the bacilli are present in large numbers. 

 It is much more difficult and often unsuccessful when the sputum is scanty 

 and mucous in character and derived from a recent lesion or again when the 

 sputum consists almost entirely of blood. As a rule, the sputum coughed up 

 by the patient in the early morning gives the most satisfactory results. 



In the case of nummular sputum it is only necessary to pick up a small 

 fragment from the centre of a purulent mass with a loop and spread it on a 

 cover-glass [or slide] in the ordinary way. The yellowish lumps found in 

 tuberculous sputum are very rich in bacilli and should therefore be selected ; 

 similarly, in mucous sputum, the solid particles suspended in the more fluid 

 portion should, as far as possible, provide the material for examination. 



It is very difficult to find the tubercle bacillus in the blood coughed up 

 during an attack of haemoptysis ; it can be more readily found in the con- 

 solidated sputum streaked with blood which is expectorated in the days 

 following the haemorrhage. 



Bacilli can seldom be detected in the sputum of persons suffering from 

 miliary tuberculosis; [it would seem that] the bacilli only pass into the 

 sputum when purulent lesions are breaking down. 



The tubercle bacillus is present also in the expectoration of tuberculous 

 cattle (Riddoch) and a good method of diagnosing the disease in cattle is to 

 collect some of the muco-purulent material from the partitions in the sheds- 

 and to examine it for the bacillus after staining in the ordinary way. 



Homogenization. When the bacilli are likely to be few in number the 

 sputum must be specially treated before they can be detected : the sputum 

 must be liquefied and made homogeneous, and then be left to deposit or else 

 be centrifuged. Under these conditions the deposit contains in a small 

 volume all the bacilli which were in the viscous mass. It is then a simple 

 matter to stain and detect them. 



1. Biedert's method. To 15-20 c.c. of sputum add 30-40 c.c. of water and a few 

 drops (6-15) of soda the thicker and more viscous the sputum the larger must be 

 the quantity of soda added. Boil the mixture in a porcelain dish until it is quite 

 homogeneous, then dilute with one or two volumes of water and boil again for a 

 minute or two. Put the mixture aside for 48 hours, then pour off the supernatant 

 fluid and prepare films with the deposit. Or, after boiling, the mixture may be 

 centrifuged and the deposit used for making films. 



2. Ilkewitsch's method. Mix 0'5 c.c. of sputum with 20 c.c. of distilled water 

 and about 10 drops of a 3 per cent, solution of caustic potash. Heat the mixture 

 in a porcelain dish but without letting it boil, stirring all the time until the mixture 

 is homogeneous. Add a little casein and a drop or two of a 3 per cent, solution of 

 caustic potash and continue the heating until the mixture has a milky appearance, 

 then pour into centrifuge tubes, add a few drops of acetic acid until coagulation is 

 just beginning, centrifuge for a few minutes and use the deposit for making films. 



3. Ellennann and Erlandsen's method. Mix 10-15 c.c. of sputum with one-half 

 its volume of a 0*6 per cent, solution of sodium carbonate in a small flask and place 

 in the incubator at 37 C. for 24 hours. Then decant the supernatant fluid and 

 centrifuge the remainder. To the deposit add 4 times its volume of 0'25 per cent, 

 soda solution, mix, centrifuge again and use the deposit for preparing films. 



According to Ellermann and Erlandsen, and Bertarelli, this method is better than 

 any other which has been described. 



4. Abba's method. Place 5-10 c.c. of sputum in a cylindrical vessel, add 15-30 c.c. 

 of a perchloride solution (perchloride of mercury, 2 grams ; salt, 10 grams ; dis- 

 tilled water, 1000 c.c.) ; mix thoroughly, centrifuge 15 c.c. of the mixture and make 

 films with the deposit. 



5. Sprengler's method. Mix 10 c.c. of sputum with 10 c.c. of warm water and a 



