34 An Introduction to Medical Mycology 



have found that when the triehophytin test is employed as part of a thor- 

 ough study of the case, including clinical and other laboratory examina- 

 tions, it is of confirmatory value both in diagnosis and in prognosis. It has 

 been said that the test cannot be useful in diagnosis since it simply denotes 

 sensitization to a dermatophyte, which may have occurred at a previous 

 time and thus have no significance in connection with a given eruption. 

 The second important disadvantage of the test is the undisputed fact that 

 it may produce a negative reaction in a patient from whose skin pathogenic 

 fungi have been isolated. Finally, the correlation of positive reactions and 

 a presenting dermatosis should be carefully interpreted, both as to exist- 

 ing probabilities and as to the presence of an active inflammatory fungous 

 disease in the past. 



It is our belief that the first criticism is not altogether founded on accu- 

 rate clinical or laboratory proof. It is probable that an inflammatory re- 

 sponse to a fungous infection is necessary before the skin becomes sensi- 

 tized. A careful study of the history for rashes will determine whether 

 such an eruption previously occurred. A thorough search usually reveals 

 traces of the condition, since spontaneous cure of most fungous diseases 

 is rare. Microscopic and cultural studies will aid in the appraisal. If the 

 examination is thorough, few instances of inability to interpret the results 

 of the test will occur. We do not believe that the test can take the place 

 of other investigations, such as the cultural determination of the pathogenic 

 micro-organism, but it may yield information which cannot otherwise be 

 elicited. 



The reason for the seeming unreliability of the test in the face of proved 

 fungous infection has already been explained (Table 4). Such a fungus 

 as A. schoenleini has a low sensitizing index, while one like T. gypseum has 

 a high index. Few patients having favus react to triehophytin; with T. gyp- 

 seum infection such a reaction is usual. 



(1) Interpretation of the intracutaneous test with trichophy- 

 tin.— When a pathogenic fungus is isolated, a positive reaction to the test 

 is additional evidence that an eruption at a remote point is also fungous. 

 In cases in which the response to triehophytin is vigorous the prognosis is 

 favorable. A strong reaction to the test should lead to conservative methods 

 of treatment, such as application of bland wet dressings, soaks, powders, 

 soothing lotions, pastes or ointments, and when there is exudative derma- 

 titis the use of roentgen rays may be considered. In a small percentage of 

 cases, the reason for the development of cutaneous sensitivity to triehophy- 

 tin cannot be determined from the history, the examination or concurrent 

 laboratory investigation. Of 111 patients who presented inflammatory erup- 

 tions on the feet but no other rashes and lor whom the microscopic and 



