CONDITIONS AND REACTIONS DEFINING DYE BACTERIOSTASIS

Abstract

Data are presented supporting the idea that the bacteriostatic action of dyes is due to a reversible equilibrated chemical reaction between dye and bacterial substance or one of its components. The limiting effective dilution of basic dyes increases with alkalinity and with basic strength of dye. The reaction is reversible, for when an inoculated tube containing an inhibiting concentration of basic dye at a high pH was brought to a lower pH, keeping the dye concentration constant, growth followed. In case of acid dyes, their effectiveness increases with acidity and with acidic strength of dye, and is reversible. Practically, the results indicate the necessity of governing the concentration of dye bacteriostat by the reaction of the medium. The reversibility of the bacteriostatic action indicates necessity of maintaining, clinically, dye concentration for considerable periods, that is, the necessity for repeated injections in cases of intravenous use.