CHAPTER V 



Methods of Diagnosis of 

 Fungous Disease 



THE procedures to be described are the chief methods by which it is 

 possible to determine the presence of fungi in specimens, to identify 

 species and to decide on their pathogenicity. 



1. THE DIRECT EXAMINATION 



This is the simplest and yet the most important single means of labora- 

 tory investigation. It is the first step in establishing a diagnosis. Its limita- 

 tion is that it rarely permits one to identify species. The method consists 

 in mounting specimens of skin, hair, nail scrapings, pus or exudate and 

 examining them under the microscope. 



2. CULTURAL METHODS 



(a) Giant colonies.— Material containing fungi, if planted on suitable 

 culture mediums, yields characteristic colony growths. In many instances 

 identification of species can be satisfactorily made in this way alone. 



(b) Culture mount (hanging-drop, slide culture).— The character 

 of the spores and the presence of any vegetative variations can be studied. 

 A small amount of material from a cultural growth is mounted and imme- 

 diately examined or inoculated in a thin medium, which can be studied as 

 growth progresses. 



3. FILTERED ULTRAVIOLET RADIATION 



The phenomenon of fluorescence may be used in the examination of 

 patients to determine the presence of tinea capitis or of tinea versicolor. 

 It may also be used in the study of fungus colonies. 



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