292 An Introduction to Medical Mycology 



and intertwined. At the level of the surface of the scalp, some spores may 

 be found. Presence in scales has not been observed. 



(b) Cultural characteristics.— Growth is slow. Initially, after isolation, 

 the colony is compact and golden yellow. Some strains have a reddish 

 tone (Plate II, facing p. 227). The center becomes elevated. Irregular con- 

 volutions and radial grooves extend to the edge. The edge of the colony is 

 depressed in a narrow band beneath the surface of the agar. The elevated 

 central portion is glabrous, and the remainder of the colony except the 

 narrow edge is downy white. 



(c) Culture mount.— There is a paucity of spores. Aleurospores are 

 few and atypical. Both terminal and intercalary chlamydospores are pres- 

 ent. There are some racquet cells and occasional rudimentary pectinate 

 bodies. The bulk of the mycelium is composed of closely intertwined, 

 irregularly sized filaments with many protuberances. 



(d) Filtered ultraviolet rays.— The infected hairs do not fluoresce. 

 The cultural growth at one month in dextrose agar shows a light yellowish 

 tan. The submerged periphery shows a bright cream color. 



( e ) Animal inoculation.— No laboratory animal is susceptible. 



(f ) Differential diagnosis.— A fungous infection caused by this micro- 

 organism should be suspected when the patient comes from the Orient. 

 The infection may be widespread. The tendency to hair destruction down 

 to the surface of the scalp may cause confusion with alopecia areata. The 

 lack of fluorescence of the hairs, the cultural appearance, the fluorescent 

 characteristics of the colony and the lack of spindle spores in the culture 

 mount suffice to differentiate it from other Mierospora. 



5. ACHORION (TRICHOPHYTON) SCHOENLEINI 



This fungus, the cause of favus, is of widespread occurrence, being com- 

 mon in Russia and other European and Asiatic countries. It was formerly 

 prevalent in Scotland and France but is less so now. In the United States 

 it has been isolated mainly in immigrants or their families. There are sev- 

 eral areas, however, where favus is endemic. 



(a) Clinical characteristics.— The scalp, the nails and the smooth 

 skin may be affected. In the scalp, typical scutula may be observed, a thick 

 diffuse crusting may be present, or seborrhea-like scaling alone may de- 

 velop. The alopecia is patchy, and long hairs may usually be observed in 

 the areas of infection. Scarring and permanent alopecia are the sequelae. 

 On the smooth skin, scutula may develop, or vesicular lesions (favus her- 

 peticus) or scaly dull red plaques may be observed. Infection of the nails 

 m;i\ be indistinguishable from onychomycosis due to other fungi. 



