

THE FATE OF BACTERIA OF THE COLON-TYPHOID 

 GROUP ON CARBOHYDRATE MEDIA 



O. ISHII 



From the Research Laboratory, Western Pennsylvania Hospital, Pittsburgh, 



Pennsylvania 



Received for publication April 7, 1920 



In any study of the fermentation reactions of the colon-typhoid 

 group on carbohydrate culture media, it is customary for bac- 

 teriologists to make observations as to the quantity of acid, alkali, 

 or gas formation for an unlimited number of days, sometimes for 

 two weeks, or one month, or even for a much longer period. In 

 this study we have found, however, that the organisms of the 

 colon-typhoid group do not live as long as this on certain sugar 

 culture media. 



The technique used was as follows. The culture media con- 

 taining the sugar were made with 1 per cent peptone plus 0.5 

 per cent sodium chloride, and they were sterilized once in the 

 autoclave under 15 pounds pressure for fifteen minutes; this does 

 not interfere with the differential fermentation reaction of these 

 sugars, as we always have been able to differentiate quite satis- 

 factorily the several strains of the colon-typhoid group with the 

 above method. 



Stock cultures were used and fresh subcultures were made in 

 broth culture media. From the latter the sugar culture media 

 were inoculated. The culture tubes were closed with cotton 

 stoppers and kept in an incubator at 37°C. They were examined 

 every day by the streak method on the plain agar plate, also in 

 broth media, one loopful of the bacterial culture being taken 

 from the sugar medium to determine whether or not the organ- 

 isms were still living. 



The results show that the period of life of the colon-typhoid 

 group on certain of the different sugar cultures is short and on 



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JOURNAL OF BA.CTHBIOLOOY, VOL. V, NO. 5 



