A NOTE ON THE VIABILITY OF MENINGOCOCCI ON 

 YEAST AGAR MEDIUM 



FREDERICK EBERSON 



Washington University School of Medicine, Saint Louis 



Received for publication March 13, 1920 



In 1918, the writer showed that a simple yeast medium (extract 

 of baker's or brewer's yeast) could be used for prolonging the 

 viability of the meningococcus. The medium possesses the 

 advantages of requiring no meat infusion or meat extract or 

 peptone. It is prepared with agar as a base and is to be used 

 in the solid or semi-solid form. Observations at the time were 

 extended over a period of six, and in several instances over a 

 period of eleven weeks. More than twenty strains of meningo- 

 coccus, recent and old, representing normal, irregular and para 

 types isolated from the spinal fluid and the nasal mucosa, were 

 tested on the solid medium and were found fully viable after 

 six weeks on the average and for some strains which were observed 

 beyond that time, for eleven weeks, when stored at 37°C. At 

 room temperature, observations were made for one month only 

 and at the end of this time, cultures were still viable. It was 

 believed that a semi-solid medium was best adapted for unusually 

 prolonged viability of organisms such as the meningococcus and 

 other species. 



Some recent observations which I wish to report, point to 

 yeast media as a valuable adjunct in routine bacteriological 

 work, particularly in view of the fact that others, notably Ayers 

 and Rupp recently, have confirmed the adjuvant properties of 

 yeast extracts in culture media. 



Representatives of the normal, irregular and para types of 

 meningococcus were seeded in semi-solid yeast agar prepared as 

 described in earlier articles by the writer, and stored at 37°C. 

 and at room temperature (24° to 26°) after a preliminary incu- 



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