Characteristics of Pathogenic Fungi 315 



r. I BLIOGH \ Pin 



Moore, M.: Malassezia Furfur, cause ol tinea versicolor: Cultivation ol organism and experi 

 mental production ol disease, \xch, Dermat. & Syph. 11:253, 1940. 



15. ACTINOMYCES MINUTISSIMUS (MICROSPORUM MINUTISSIMUM) 



This is the micxo-organism causing erythrasma. 



(a) Clink \i characteristics.— Erythrasma is characterized by super- 

 ficial scaly plaques, well demarcated from normal skin by a reddish border. 

 The lesions are yellowish to brown. The disease is usually localized to one 

 or both of the axillae or the groins or to other intertriginous parts. 



(1)) Immunologic reactions.— There is no sensitization to trichophytin. 

 Sensitization to the cultural organism has been reported, but this is ques- 

 tionable. 



(c) Microscopic features.— The scales may be examined after the slide 

 is stained (see p. 236). The fungous elements are too small to be seen under 

 the usual low power magnification. Under high power magnification one 

 may make out fine threads. On examination with the oil immersion lens, 

 the threads appear long, tortuous and interlacing; segmentation may be 

 noted. A few round spores may be seen. Granules are occasionally visible. 



(d) Cultural characteristics.— We have not been able to grow 

 the organism on artificial mediums. According to Poehlmann, however, 

 several investigators have been able to do this. 



(e) Filtered ultraviolet rays.— The rash caused by this micro-organ- 

 ism does not fluoresce, its appearance being similar to that observed in 

 ordinary light. The appearance of the cultural growth is unknown. 



(f) Animal inoculation.— We have not had any personal experience. 



(g) Differential diagnosis.— The micro-organism is so small that it may 

 be mistaken for an incidental bacterial contaminant. No other species of 

 fungus can be confused with it. 



16. ENDODERMOPHYTON TROPICALE 



This is the chief cause of tinea imbricata. Other fungi also reported to 

 be pathogens (E. indicum and E, concentricum ) are probably variants. 



(a) Clinical characteristics.— Tinea imbricata is a superficial mycosis 

 seen commonly in the tropics and in some temperate zones such as North 

 China (F. Reiss). It is characterized by pruritic ringed lesions and profuse 

 scaling. The nails may be involved. The hair follicles are never invaded, and 

 suppuration is unknown. 



