334 An Introduction to Medical Mycology 



face of dextrose agar and incubated at room temperature. Growth on this 

 or on other common laboratory mediums is usually not difficult to accom- 

 plish. Within a few days a moist area appears. A creamy- white fluff soon 

 covers the area, and growth is moderately rapid. The colony becomes 

 brownish with age. 



(e) Culture mount.— There is a profuse growth of coarse mycelium 

 (not observed in fresh preparations from the tissues). Coccidioides im- 

 mitis is definitely septate, even in early colonies. Arthrospores and chlam- 

 ydospores are to be observed. Identification of the organism in its cultural 

 form can be made with certainty only by animal inoculation. 



(f ) Filtered ultraviolet rays.— The appearance is unknown. 



(g) Animal inoculation.— Nearly all laboratory animals are suscep- 

 tible. The guinea-pig is usually used. This animal is not nearly so sus- 

 ceptible to B. dermatitidis, the organism usually to be distinguished from 

 C. immitis. 



(h) Differential diagnosis.— In human beings the organism should be 

 differentiated from B. dermatitidis, P. brasiliensis, Rhinosporidium, Lyco- 

 podium and amebic cysts. In C. immitis the wall is thick, and endospores 

 will be observed. In B. dermatitidis the wall is not so thick, and there is 

 budding. In P. brasiliensis there are no endospores in the tissues, but the 

 organism appears as budding cells in clusters. Animal inoculation is also 

 more difficult to attain than with C. immitis. Rhinosporidium forms endo- 

 spores in large numbers which are discharged through a definite opening; 

 no cultural growth has yet been observed. Lycopodium spores resemble 

 dusting powder, and amebic cysts may be confused. 



25. PARACOCCIDIOIDES BRASILIENSIS 



This is the cause of granuloma Paracoccidioides, a rare disease endemic 

 in South America. It has probably not been recognized elsewhere. 



(a) Clinical characteristics.— The cutaneous lesions resemble those 

 of granuloma coccidioides or of blastomycosis. The initial lesions are seen 

 around the mouth, there is marked adenopathy, and if generalization occurs 

 the intestines may be affected. These points clinically distinguish granu- 

 loma Paracoccidioides from the other two diseases. 



(b) Microscopic features.— The organism appears in tissue as a round 

 cell, with multiple small buds (in blastomycosis, only one bud develops). 

 No round form containing endospores is noted in tissue (in contrast to 

 C. immitis). 



(c) Cultural characteristics.— Growth is slow. At 37 C. on blood agar, 

 the colony is small, cream-colored, yeastlike, compact and sharply demar- 



