BACTERIAL VACCINES 217 



In properly selected cases, when properly administered, tuberculin will often 

 establish the nature of a tubercular infection when other methods of diagnosis 

 fail to. 



Tuberculin, like other bacterial products, is a potent agent capable of bene- 

 fiting or seriously injuring those treated with it. 



It should only be administered by those familiar with its properties and ex- 

 perienced in immunology. 



Koch's old tuberculin is the tuberculin of choice for diagnostic purposes. 

 There are different methods of using it. Its value is based on the fact that, 

 when properly administered, a localized or general reaction occurs in tuberculous 

 patients and no reaction occurs in the non- tuberculous. 



For diagnostic purposes tuberculin is injected subcutaneously, rubbed into 

 a scarified cutaneous surface, rubbed into the skin where there is no breach of 

 continuity, or dropped into the eye. Special advantages are claimed for each 

 of these methods and each has its limitations. 



The subcutaneous administration of tuberculin gives the most accurate re- 

 sults. It is strictly contraindicated when the patient's temperature is above 

 normal and perhaps should not be used to diagnosticate tuberculosis in children 

 under 10 years of age. Successful employment depends upon accurate observa- 

 tion of the patient's temperature and physical signs before and after the injec- 

 tion of tuberculin. 



The degree of reaction manifest by a tuberculous patient following an injec- 

 tion depends upon the sensitiveness of the patient and the size of the dose. 

 This reaction may be nothing more than inflammation at the point of inocula- 

 tion, some or all of the symptoms and physical signs of disease may be aggra- 

 vated, there may be a rise of temperature from o.5F. to 2F., or, in a severe reac- 

 tion, all these manifestations may be observed. 



The endeavor of the diagnostician is to obtain a distinct reaction, but as slight 

 a one as possible; a rise of temperature greater than iF. is always to be avoided. 



Different patients vary to a great degree in sensitiveness to tuberculin, hence 

 the initial dose must be less than could injure the most sensitive, consequently 

 the first, perhaps the second injection, will not cause a reaction in the majority 

 of tuberculous patients. 



The technique of the subcutaneous tuberculin test is as follows: 



The patient's temperature is taken every 2 hours for i or 2 days before in- 

 jecting and symptoms and physical signs are carefully noted. 



The first injection should be o.oooi cc. or less. Following the injection the 

 patient's temperature should be taken and the physical signs noted every 2 or 

 3 hours for 24 hours. If no reaction is caused by the first injection a second 

 test is made after an interval of 48 hours, using o.ooi cc. If the second test is 

 negative, subsequent tests are made at intervals of 48 hours, using 0.002 cc., 

 0.003, -o4> o-5> 0.007, 0.009. 



Should there be reason to suspect tuberculosis, in spite of negative reactions 

 obtained with tuberculin from the human type, then the tests may be repeated, 

 using tuberculin from the bovine type of the tubercle bacillus. 



