THE TUBERCLE BACILLUS 97 



Tuberculosis, due to the bovine tubercle bacillus prevails extensively 

 among domestic cattle. Dogs, cats, horses, sheep and goats occasionally are 

 infected. 



DIAGNOSIS 



Examination of Sputum. The patient is supplied with a clean, sterile, wide- 

 mouthed container for the collection of. the sample. That which is expector- 

 ated during the early hours after arising from sleep is most apt to contain tubercle 

 bacilli; hence, the patient is directed to collect it. If expectoration be scant 

 it may be an advantage to collect the output of an entire day. 



When received, the sputum is inspected and if pearl-like bodies or particu- 

 larly dense portions are observed these are selected for examination, as being 

 the most likely portions in which to find bacteria. If the sputum is homo- 

 geneous it should be thoroughly shaken before removal of a portion. 



The selected particle of sputum is lifted with a sterile platinum loop and 

 placed upon a clean glass slide or cover glass; if fluid it can be readily spread in 

 a thin, even film with the platinum loop; if tenacious or granular an even film 

 is obtained by placing a loopful of sputum on a slide, dropping a second slide 

 on top of it and then drawing the slides apart. 



When the sputum has been spread in a thin, even film on the slide or cover 

 glass it is fixed to the slide either by letting it stand in the room until dry, or 

 gently heating over a flame until dry. After fixing by either of these methods 

 it is stained by one of the methods devised to show the acid- and alcohol-fast 

 properties of the tubercle bacillus, previously described. 



If examination of slides so prepared fails to disclose the presence of tubercle 

 bacilli it does not necessarily indicate that the sputum is free from them; it 

 merely shows that if present they are scant and not found in all portions of the 

 sputum. Under such circumstances the sputum should be treated as follows: 



Add an equal volume of sterile water, shake until homogenized, centrifu- 

 galize at high speed for ^ hour and make smears of sediment for staining and 

 microscopic examination; or: 



Add antiformin to the entire sample of sputum (i cc. of antiformin to 4 cc. 

 of sputum), mix by shaking and place in incubator for 8 to 24 hours; centri- 

 fuge until a precipitate is thrown down, take off the supernatant fluid with a 

 pipette, replace it with sterile water, shake the tubes to thoroughly mix the 

 sediment with the water and spin again until complete precipitation; in this 

 manner wash the precipitate several times; then, smear it on a slide and fix 

 and stain the same as sputum. 



Antiformin dissolves practically all the sputum and all bacteria except the 

 tubercle bacillus; with it we can concentrate all the tubercle bacilli that might 

 be present in 50 cc. of sputum into a precipitate of less than i cc. 



It is to be remembered that a tuberculous person may only occasionally 

 expectorate sputum containing tubercle bacilli. Failure to find tubercle bacilli 

 in sputum from a suspected patient should not be considered significant until 

 samples have been obtained and examined on several consecutive days. 



