302 An Introduction to Medical Mycology 



(h) Differential diagnosis.— See the two preceding sections on T. vio- 

 laeenm and T. crateriforme for a discussion of their characteristics. 



BIBLIOGRAPHY 



Slaughter, J. C, and Cawley, E. P.: Infection of glabrous skin instigated by the fungus 

 Trichophyton sulfureum, J. Invest. Denuat. 9:63, 1947. 



10. TRICHOPHYTON GYPSEUM 



The chief fungi causing intertriginous infections as well as infections of 

 the nail are T. gypseum and its variants, T. purpureum, and E. inguinale 

 ( floccosum ) . While other species are occasionally isolated from the feet, 

 they are so rare as to be of little practical importance. 



At the outset, it should be noted that T. gypseum is unstable and given 

 to the development of variants. It is by no means certain that placing to- 

 gether the various growths in this one species is the final solution. One 

 might consider T. interdigitale (Kaufman-Wolf) to be a pleomorphic form 

 of T. gypseum. Weidman has observed a periodic transition from a fluffy 

 to a powdery and back again to a fluffy condition in a growth isolated from 

 his own toes. Emmons used monospore cultures of M. fulvum from which 

 were produced six types of colonies; these were morphologically different 

 from each other and from the original growth. We have observed that when 

 a granular form of T. gypseum is subcultured it tends to become more fluffy. 

 This change may also be apparent in circumscribed sectors. If material 

 from two sectors is transplanted, the character of each sector is retained. 

 Besides the type usually isolated we recognize three other types which 

 are probably derivatives or at least closely related: (1) a granular type; 

 (2) a white fluffy growth (T. interdigitale), and (3) a white compact 

 growth (T. niveum). Besides the interchanging types of growth (granular 

 or fluffy) which have been noted at different times in cultures of material 

 from the same infection, other evidence has accumulated that the types of 

 T. gypseum mentioned here are closely related. The pigmentation in the 

 subsurface portion of the colony is similar in all types, provided the same 

 batch of dextrose agar is used. This is characteristically a dull rose-tan. 



(a) Clinical characteristics.— Most of the inflammatory intertriginous 

 and spreading fungous infections of the feet are caused by this species of 

 fungus. The toe nails are also commonly affected, and rarely one or more 

 of the finger nails may be involved. Other intertriginous parts of the body, 

 such as the groin and the axilla, may also become the seat of the disease. 

 Trichophytids produced from intertriginous foci are usually initiated by 

 this species of fungus. The downy types rarely affect hair follicles; the 



