Quantitative Gram Reaction

Abstract

At the present time there is no satisfactory procedure for estimating the degree of gram positivity although the need for a quantitative method is widely recognized. Recently Kennedy and Barbaro (1953) reported an accurate and reproducible method for determining quantitatively the adsorption of crytl violet by bacteria. In addition, the effect of the species and strain of the organism used, the method of killing the cells, and the time in contact with the dye on the quantitative adsorption of crystal violet were studied. The present report describes the application of this quantitative procedure to the gram reaction, the effect of dye concentration on the quantitative adsorption of crystal violet, and the significance of the dye concentration and the counterstain in the gram reaction.