THE DIFFERENTIATION OF LACTOSE FERMENTING 

 ANAEROBES FROM B. COLI 



REUBEN L. KAHN 



From the Department Laboratory, Southeastern Department, United States Army, 



Atlanta, Georgia 



Received for publication June 17, 1918 



The procedure commonly employed for the differentiation of 

 anaerobes from B. coli consists largely of a repetition of the 

 presumptive and confirmatory tests of the committee on Stand- 

 ard Methods, (1917). Thus, according to Frost, (1916). 



If no typical colonies develop within twenty-four hours on Endo 

 plates made from fermentation tubes showing gas, further effort is 

 made to recover B. coli as follows: (1) One or more colonies are trans- 

 ferred to lactose broth fermentation tubes. The formation of gas 

 demonstrates the presence of B. coli; (2) Plates are again made from 

 the original fermentation tube; (3) A transplant is made from the 

 original fermentation directly to another lactose broth tube, if steps 

 (1) and (2) have both failed to recover B. coli, plates are now made 

 from this transplanted culture; (4) At the same time a transfer is 

 made from this tube directly to a third fermentation tube. 



If all the above procedures fail to recover B. call and gas is still 

 formed in this fermentation tube, the inference is that gas in the pre- 

 liminary test was due to an anaerobe. 



If an anaerobic lactose fermenting organism be inoculated in 

 the butt and on the slant of an Endo tube, we should theoreti- 

 cally have reddening and gas production in the butt and no 

 growth on the slant. It was observed, however, that when gas 

 formation in lactose fermentation tubes was due to anaerobes, 

 transplantations from these tubes to Endo tubes showed no 

 growth at all — either on the slant or in the butt of these 

 tubes. It seems that aside from the inability of anaerobic 

 organisms to grow aerobically on the slant, the fuchsin-sulfite 



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