ON THE VALUE OF THE PETROLEUM-ETHER METHOD 



FOR THE ISOLATION OF B. TYPHOSUS 



FROM FECES 



LAWRENCE A. KOHN and CHARLES KRUMWIEDE, JR. 

 From Bureau of Laboratories, Department of Health, New York City 



Received for publication, September 12, 1917 



The use of petroleum-ether in the isolation of typhoid bacilli 

 from feces was suggested by Bierast (1914). He added a finger's 

 breadth of petroleum to a fecal suspension in broth and shook 

 the mixture at intervals. After allowing this to stand in a cool 

 place for sixteen hours, he plated the sediment or some of the 

 broth from the bottom of the container. He reported that 2 

 out of 23 specimens were positive only by this method. The 

 work was interrupted because he developed typhoid fever. Jaffe 

 (1915) had favorable results with 24 specimens, as follows: 



He calls attention to the danger of the method and reports a 

 case of typhoid fever due to its use. 



Hall (1915) working with the method found that the activity 

 of the different fractions obtained by the distillation of crude 

 petroleum varied inversely with the boiling point. He found 

 that the fraction with a boiling point about 40°C. gave the best 

 results. This fraction would contain a large proportion of 

 pentane (C5 H12) and for convenience we shall refer to it as such. 



Hall modified the Bierast procedure as follows. To a mod- 

 erately heavy suspension of feces in broth is added one-half its 



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