I 



CULTURES 195 



unless iodides are administered. A correct diagnosis with proper 

 treatment (internal administration of iodides) leads to a prompt 

 and permanent cure. Since iodides are commonly used in the treat- 

 ment of tertiary syphilis, one may make an erroneous diagnosis of 

 syphilis in a case of sporotrichosis, and believe that the diagnosis 

 has been confirmed by the results of specific treatment. 



The diagnosis is established by demonstrating the organism in 

 the pus. In the body tissues and exudates the parasite appears as a 

 small, single-celled, spindle-shaped organism. It is most frequently 

 seen within the polymorphonuclear leucocytes. It reproduces by 

 budding at one end of the cell. In size 

 the cells are comparable to those of 

 some of the larger bacteria, but they 

 are easily recognized by their charac- 

 teristic cigar shape. They have some- 

 times been incorrectly referred to as 

 spores, but they are quite different from ' ^^^ j^^^"^ /^i^^^"^^ 

 the spores formed in cultures. They arc *^- " -'^**^- tS^^-^ 



the only structures formed in animal Fig. 99. Smear of pus from 

 tissue; no mycelium develops. They sporotrichosis, showing the par- 



„ . , . . asites withm the leucocytes. 



are far from bemg numerous m pus 



from human cases, and may be found only after prolonged search. 

 They are best looked for in smears stained by Gram's method, al- 

 though many of the cells are Gram-negative. 



Although these bacillus-like cells are never found in ordinary cul- 

 tures, according to Davis ^ they are formed in cultures in blood or 

 blood serum, especially if air is excluded or if sterile tissue is added. 



Cultures. Cultures are of more value in diagnosis than are smears. 

 Pure cultures may be readily obtained if made from pus aspirated 

 from the younger lesions which have not yet opened; with more dif- 

 ficulty from those which have developed fistulae, for in these latter 

 there is always considerable secondary infection with bacteria. The 

 fungus will not grow readily on dextrose-tartaric agar, and the 

 medium of choice is Sabouraud agar. 



The character of the growth on agar is strikingly different from 

 that of most molds. At first it is soft and creamy in texture, the 

 surface moist and shiny, whitish in color, and resembles more a cul- 

 ture of bacteria. As the culture grows older, it becomes darker in 

 color, first a light tan which gradually deepens to a coffee brown 

 and may eventually become quite black. The mass becomes firmer 

 in texture, tending to pull off the agar in rather elastic flakes, and 

 the surface becomes more and more wrinkled. Some strains remain 



