68 CLINICAL BACTERIOLOGY AND HEMATOLOGY 



ments. If you examine pus ffom a chronic abscess and find no 

 organisms of any kind, it is almost certain that the process is a 

 tuberculous one (actinomycosis and glanders, both comparatively 

 rare. diseases, may also give rise to similar negative findings), and 

 the negative evidence obtained by the failure to find tubercle 

 bacilli should not be allowed to carry much weight. The same 

 is true for the clear exudates. 



In suspected cases of tuberculosis, in which no infective 

 material is forthcoming, there are two methods which may be 

 used: (i) The estimation of the opsonic index (see p. i58), and 

 (2) the use of Koch's old tuheyculin. This is usually considered 

 to be too dangerous for practical use, but if a small dose only be 

 given (y^Vo ^o 2717 c.c), and if it is not employed on cases in which 

 there is a mixed infection, I believe the danger to be practically 

 nil. The tuberculin is sold in i-c.c. bottles. For use, add the 

 contents of one of these to 200 c.c. (about §vii.) of recently boiled 

 and cooled normal saline solution, containing about ^ per cent, of 

 carbolic acid. Mix well and inject i c.c. (about 3J minims) df 

 the fluid hypodermically. In a positive case there will be a sharp 

 reaction, the temperature rising to 103° or more, and remaining 

 elevated for a day or so. Should there be no reaction, give ^ c.c. 

 (8^ minims of the solution as prepared) in a day or two's time, 

 and if this also causes no rise of temperature finish the test by 

 giving I c.c, or 17 minims, of the solution, containing ^^^^ ^■^- ^^ 

 this causes no rise of temperature, the patient can be pronounced 

 non-tuberculous with some degree of certainty. The test is of 

 especial value in enabling us to prove the absence of the disease 

 rather than as a method of diagnosing its presence. Do not use 

 tuberculin which has been diluted more than a week. 



Tuberculin may also be used in children up to the age of 

 twelve or fourteen by von Pirquet's method. The skin (clean, 

 but not otherwise prepared) is gently scarified by means of a 

 glass pipette, lancet, or other suitable instrument, taking care 

 not to draw blood. A drop of undiluted old tuberculin is then 

 applied, well rubbed in, and allowed to soak in without being 

 rubbed off; it is a good plan to cover the area with a watch- 

 glass or vaccination shield. The area is examined in twenty- 

 four and, if necessary, in iorty-eight hours. In a negative case 

 there is practically nothing to be seen. In a positive one there 

 is a flat-topped red papule after about twenty-four hours ; the 

 redness may spread beyond the scarified area in all directions, 



