DIAGNOSTIC TESTS FOR TUBERCULOSIS 95 



Koch's "Old Tuberculin," which was simply a concentrated 5% glycerine bouillon 

 culture, is now principally used in diagnosis. It was prepared as follows: 



After four to six weeks the surface growth begins to sink to the bottom of the 

 flask. This fully developed culture is evaporated over a water-bath at 8oC. to 

 one-tenth the original volume. It is then filtered, the final product containing 

 about 40% of glycerine. 



Koch's "New Tuberculin" or tuberculin "R" was introduced in 1897. In this, 

 virulent bacilli are dried in vacua and ground up until stained smears fail to show 

 intact bacilli. One gram of such material is triturated with 100 c.c. water and 

 centrifugalized. The supernatant fluid is removed and is designated "T. O." 

 The residue is then dried, triturated in water and centrifugalized. Subsequent 

 trituration and centrifugalization, preserving each time the supernatant suspension, 

 gives the new tuberculin. It has been found at times to contain virulent T. B. 



Koch's bazillen emulsion has been more recently introduced by Koch (1901). 



This is simply a suspension of ground-up bacilli in 50% glycerine solution. 



It really is "T. O" and "T. R" combined and contains 5 mg. of bacillary 

 substance in i c.c. Another preparation is the bouillon filtrate of Denys. This is 

 the unheated Chamberland filtrate of broth cultures of human T. B. It contains 

 Y% phenol. 



In the use of T. R. and of bazillen emulsion, Sir A. Wright recommends doses 

 of Kooo nig., and he rarely goes beyond Kooo rng. in treatment. These prod- 

 ucts come in i c.c. bottles containing 5 mg. of bacillary material. It is convenient 

 to remove %o c -c., containing i mg. Add this to 10 c.c. of glycerine salt solution 

 with %% of lysol. Each c.c. contains Ko nig. One c.c. of this stock solution 

 added to 99 c.c. of salt solution, with Y% of lysol, would give a working solution, 

 each c.c. of which would contain Mo 00 m S- of tuberculin. 



For diagnostic tuberculin reactions we have the following: 



1. Subcutaneous injection of J mg. If no reaction occurs in four 

 or five days we may increase to i to 5 mg. 



Positive reactions show (a) constitutional symptoms of fever, malaise and possibly 

 chill; (6) focal symptoms, as when a tuberculous gland, joint or skin involvement 

 becomes active, and (c) local reaction as shown by the tenderness, induration or 

 inflammation at the site of injection. 



2. Variations in opsonic index. 



3. Instillation into one eye of a drop of J% or i % solution of puri- 

 fied tuberculin. 



Reaction is shown by redness, especially of inner canthus, in twelve to twenty- 

 four hours (Calmette). A previous instillation may sensitize a nontuberculous case 

 and a second application of the drop may give an erroneous diagnosis. This test 

 should not be used in persons over fifty or when there is any disease of the eye to be 

 used or for that matter of the other eye. For instance, in corneal opacities, due to 

 T. B. keratitis, a focal reaction would occur. 



