276 



BACTERIOLOGY FOR NURSES 



FIG. 42. Yeast Cells. 



budding the nucleus moves to the edge of the cell and commences 

 to divide. Soon a protrusion appears which rapidly develops into 

 a daughter cell of the same shape and size as the mother cell. 

 Under certain conditions many yeasts are able to reproduce by 

 spore formation ; the nucleus divides usually into four portions, 



each of which becomes the cen- 

 ter of a new cell lying within 

 the parent cell (Fig. 42). 



Pathogenic Yeasts. Busse 

 in 1894 was the first to report 

 the pathogenicity of a yeast 

 to which was given the name 

 Saccharomyces busse. In the 

 case he studied the first lesion 

 appeared in the form of an 

 abscess on the tibial bone. 

 Thirteen months later the pa- 

 tient died from a generalized 

 yeast infection, and on autopsy the yeast was found in lesions in 

 the ulna, lung, kidney, and spleen. 



Since the discovery by Busse many similar infections have 

 been reported. In most cases a small papule first appears with a 

 moderate indurated area surrounding it; later a pustule forms 

 which discharges yellowish pus. The lesion spreads slowly, and 

 as it invades fresh tissue the older areas show a tendency to heal. 

 The organisms may be readily demonstrated in film preparations 

 made from pus in the usual manner and stained with methylene 

 blue. For their cultivation glucose agar is the most suitable 

 medium. They are isolated with difficulty from material in which 

 bacteria are growing because they develop more slowly than the 

 latter. Repeated plating and the use of high dilutions is generally 

 necessary for their isolation. 



The tumor-like growths in some forms of blastomycosis has 

 led certain observers to assume a relationship between these or- 

 ganisms and cancerous growths. The assumption has not yet 

 been supported by satisfactory evidence. 



