The Correlation of the Voges-Proskauer and Methyl-Red Reactions in the Colonaerogenes Group of Bacteria

Abstract

Bacillus coli was firs.t isolated by Escherich, from the feces of a cholera patient in 1884. It was soon recognized as a normal inhabitant of the intestinal tract of man and other animals, and for the past two decades the colon-aerogenes group of bacteria has attracted considerable attention from bacteriologists; particularly those interested in sanitation. Numerous attempts have been made to differentiate colonlike bacteria from different sources by their cultural characteristics, by agglutination reactions, complement-fixation tests, pathogenicity, etc., but until very recently the results were so uniformly negative that the entire group of lactose-fermenting bacteria is held, by some, to be characteristically of intestinal origin. In routine water and milk analyses the presence of colon-like organisms is regarded, by many, as an index of pollution. There is considerable evidence accumulating, however, to show that the animal intestine is not the sole and exclusive habitat of colon-like bacteria. Prescott,1 in this country, and Papasotiriu,2 in Germany, report the presence of colon-like organisms on grains of various kinds. Prescott regards those from grain and feces as identical. He believes that multiplication actually takes place on the grain and that their presence cannot be explained by contamination from the air and dust. Rogers and his co-workers3 of the U. S. Department of Agriculture have recently isolated 166 specimens of colon-like bacteria from 33 samples of dry grain (corn, barley, wheat, and oats). They also obtained 14 cultures from 2 samples of green oats, which had been opened aseptically, and are therefore inclined to believe that these were growing in the milk of the immature grain. In view of the fact that organisms which are apparently B. coli are not uncommon on grains, their presence in water and milk cannot be regarded as prima facia evidence of fecal contamination. Some