CHAPTER XXXV 



Fungi Questionably Pathogenic 



1. SAPROPHYTES ASSUMING PATHOGENICITY 



UNDER this heading might be placed instances of infection in which 

 fungi are secondary invaders and it is difficult to determine whether 

 their presence is more than incidental. It is our opinion that much harm has 

 been done and the progress of medical mycology has been delayed because 

 of the confusion due to the numerous case reports of supposed mycoses. 

 After a critical analysis of many of these reports, one concludes that proof 

 was frequently insufficient. It is probably true, of course, that the difference 

 between pathogenic and purely saprophytic existence is not great; factors 

 of lowered resistance of the host or the development of a strain of increased 

 virulence may account for a certain number of genuinely mycotic infections. 

 It would probably be wise, however, to be skeptical regarding claims of 

 pathogenicity of fungi of ordinarily nonpathogenic species unless more proof 

 of their pathogenicity is offered than their mere occurrence in diseased 

 tissue. Such tissue is suitable soil for growth and propagation of fungi, 

 but in this they may fail to affect the normal tissues of the host. The 

 ideal procedure would be reinoculation of the living organism into healthy 

 human tissue; but this is not often possible, nor is it desirable in every 

 ease. Animal inoculation can never be as valuable a procedure, since the 

 susceptibility to infection is not the same even in different species of ani- 

 mals and is not likely to be the same in animals as in human beings. Re- 

 peated isolation of a particular species of fungus, even if it is commonly sap- 

 rophytic, is likely to impress the worker unduly, and the need for further 

 proof is not considered necessary. It would be helpful if, when the diagno- 

 sis is based solely on the isolation of a fungus, the reporter would use a 

 question mark in the title to indicate doubt as to the diagnosis. 



In a case of deep nodular and ulcerating lesions from which Scopulariop- 

 sis brevicaulis (a saprophyte found on vegetable and other organic matter) 



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