CHAPTER XXX 



The Trichophytin Test 

 Technical Details 



IF UNIFORM results are to be obtained from the test, a number of 

 details must be carefully considered and the exact teclmic should be 

 mastered. The test is perhaps as difficult to perform as an accurate white 

 blood cell and differential count. The main technical considerations are as 

 follows: 



1. The syringe and needle should be freshly sterilized. 



2. The vaccine should be free from contamination. The addition of 0.5 

 per cent phenol to the test solution is a practical way of assuring sterility. 

 Boiling a solution of trichophytin does not appear to affect its potency. 

 Reactions to ordinary trichophytin and to trichophytin heated two hours 

 in a steam bath were identical. 



3. The concentration of the trichophytin should be as low as possible 

 while still capable of eliciting reactions in sensitive persons, such as Metz 

 1:100 or Lederle 1:30. 



4. As a rule the use of one of several commercial extracts is preferable 

 to the use of a homemade product, which is difficult to standardize. It has 

 been noted that a person sensitive to an extract made from one species of 

 Trichophyton usually reacts to an extract made from another species. 



5. The vaccine should be carefully introduced intracutaneously. Exactly 

 0.1 cc. of the test material should be given. 



6. Observation of the patient for the presence of a reaction should be 

 made after 10 or 15 minutes (for an immediate wheal reaction), after 48 

 hours (for the usual eczematous response) and again at the end of one week 

 (for sustained and delayed reactions). 



7. The degree of reaction should be judged not by estimation but by 

 measurement, with a rule, of the diameter of the area of skin affected. We 

 found it difficult to set a standard for the immediate wheal responses. The 



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