Methods of Diagnosis of Fungous Disease 



IT) 



12. AUTOINOCULATION 



Recovery of a recognized pathogen from a characteristic lesion is suffi- 

 cient to establish the organism as the cause of the infection. II the lesion is 

 atypical, particularly if the isolated fungus is of a variety not usually patho- 



Fig. 3. Hyphal fusion between two strains of identical species. This does not occur when 

 strains of dissimilar species are in proximity. A, T. gypseum. B, M. audouini. (Courtesy of 

 Harold Orr and Silver Keeping, Edmonton, Alberta, Canada.) 



genie or not usually isolated, further proof of pathogenicity is ordinarily 

 required. Here the use of animals may be instructive but is not in itself 

 conclusive, since variation in susceptibility with the species of animal shows 

 that the response in human beings also varies. As mentioned by Weidman 

 and others, the more frequent use of experimental autoinoculatiOn is advis- 

 able. It is common knowledge that there is a considerable flora of contami- 

 nants, and it is possible that on occasion pathogenic strains may appear 

 among them. 



13. ROENTGEN EXAMINATION 



This may give the first clue to the nature of the pathologic process. 

 Pulmonary mycoses usually affect the base of the lung, and cavitation is 



