A SIMPLE AND PRACTICAL MEDIUM FOR DIFFEREN- 

 TIATING B. TYPHOSUS, B. PARATYPHOSUS A., B. 

 PARATYPHOSUS B., B. ENTERITIDIS, AND B. COLI 



KAN-ICHIRO MORISHIMA 



From the Quarantine Laboratory, Port of New York, Health Officer's Department, 



Rosebank, New York 



Received for publication May 14, 1917 



Before the war in Europe began paratyphoid fever was rela- 

 tively rare, but owing partly to prophylactic inoculation against 

 typhoid, it soon became more common among soldiers than the 

 latter disease. With increased prevalence there is need of 

 •simple cultural tests for the recognition of the causative organ- 

 isms. A number of such tests have been devised. Russell's 

 double sugar medium, consisting of litmus agar with 1 per cent 

 lactose and 0.1 per cent glucose, is widely used to receive the 

 fishings of suspicious colonies. It differentiates the paraty- 

 phoids and B. enteritidis from B. typhosus and the B. coli group, 

 but does not differentiate between B. paratyphosus A, B. para- 

 typhosus B., and B. enteritidis. To determine which of these 

 latter organisms is present, further inoculation of the culture 

 into litmus milk, lead acetate agar, or other special culture 

 media, and agglutination tests must be resorted to. 



It occurred to me that by pouring one agar medium into a 

 test tube and allowing the agar to soUdify, and then pouring a 

 layer of a second differential agar medium upon this, a medium 

 would be obtained which would furnish, in twenty four hours, 

 more information from a stab fishing than do the media at pres- 

 ent employed. Of a large number of such combinations, the 

 following proved to be the most satisfactory. 



Meat infusion agar is prepared in the usual way, cleared with 

 egg-white, and titrated while hot to about —0.2 to —0.4 with 

 phenolphthalein as an indicator. A 2 per cent solution of neu- 



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