The Voges-Proskauer and Correlated reactions Of Coli-Like Bacteria
Journal of Infectious Diseases
It is becoming increasingly apparent that all nonsporing, lactosefermenting bacteria are not of equal sanitary significance. There is no doubt that a water containing .the relatively nonresistant B. coli communis and B. communior, or their very close allies is more objectionable and dangerous than one containing only the more ubiquitous and ·quite resistant B. aerogenes or B. cloacae. These 2 groups of lactosefermenting organisms should be differentiated, and studies on rapid methods for their
... solation, separation, and identification are sorely needed. It is the primary purpose of this. paper to record the results of attempts to hasten the Voges-Proskauer reaction and to point out -its apparent correlation with the fuchsin-aldehyd test. THE FUCHSIN-ALDEHYD REACTION If an aldehyd is added to a solution of basic fuchsin, decolorized with sulphurous acid, a distinct red to violet color appears usually in less than 1 or 2 minutes. This reaction is accepted by chemists as specific for aldehyds and is universally employed as a group test. In .all probability, the red coloration on Endo agar, so characteristic of B. coli, is merely a localized fuchsin-aldehyd test. It should be noted, however, that in the Endo medium, the fuchsin is decolorized with Na 2SO a and not with H 2SO a . At the suggestion of Dr. R. E. Buchanan, this reaction was tried with a number of coli-like organisms to determine if it is of any differential value. All of the organisms studied were isolated from soil. The test was made as follows: To 2 c.c. of a 72-hour culture of the organism in 0.5% carbohydrate-peptonedipotassium-phosphate solution, were added 2 or 3 drops of basic fuchsin decolorized with sodium sulphite. A slight pink coloration was recorded as negative while a distinct red or cherry color was recorded positive. The results are shown in Table 1 .