A CULTURE MEDIUM FOR MAINTAINING STOCK 

 CULTURES OF THE MENINGOCOCCUS^ 



C. G. A. ROOS 

 From the Mulford Biological Laboratories, Glenolden, Pa. 



The maintenance of certain pathogenic bacteria upon artificial 

 culture media is sometimes attended with great difficulty. 

 Among these organisms the meningococcus may be said to occupy 

 the first place. Its peculiar biology — particularly its intra-cellu- 

 lar ferment which is so potent a factor in its destruction — makes 

 its viability at all times precarious. Furthermore its highly 

 parasitic nature requires highly complex substances such as those 

 upon which it grows in the human body. 



While strains of the meningococcus that have been accustomed 

 to artificial cultivation may be maintained upon plain nutrient 

 agar, this medium is not favorable to its continued cultivation; 

 the addition of glycerine offers no advantage; glucose results 

 in more rapid growth and consequently more rapid degeneration. 

 In their early work Councilman, Mallory and Wright used Loef- 

 fler's blood serum for both isolation and maintenance. Flexner 

 used plain agar to which sheep serum was added. Some authors 

 have used the serum of other animals — horse, goat, calf. Human 

 serum and human ascitic fluid are conceded to be superior for 

 isolation and for obtaining massive growth. The addition of 

 the whole blood is possibly better than serum alone. Kutscher 

 recommends a medium prepared with human placenta to which 

 is added calf serum and glucose. For isolation Conradi used 

 the centrifugaHzed spinal fluid, adding one part of the super- 

 natant liquid to three parts of shghtly alkaline nutrient agar; 

 upon this solidified medium he planted the sediment. 



1 Presented at seventeenth annual meeting of the Society of American Bac- 

 teriologists, Urbana, 111., December 28, 1915. 



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