The “Reversal,” Neutralization, and Selectivity of Germicidal Cationic Detergents

Abstract

The germicidal action of cationic detergents against Gram-positive and Gram-negative bacteria could not be reversed by the anionic detergents Na lauryl sulfate or Na decyl sulfate. In bacteriostatic tests with Gram-negative bacteria, addition of an anionic detergent did result in the growth of cultures inhibited by the cationic detergent. However, the action of the anion was not that of a reversal agent; there was merely an interruption of the continued action of the cationic germicide against the remaining viable bacteria. In bacteriostatic tests with Gram-positive bacteria, anionic detergents, when added either before or after the cationic detergent, had no inhibitory action on the bacteriostatic action of the compound. The anionic detergent merely delayed the killing action of the cationic germicide. The cationic detergent Zephiran in bacteriostatic tests was over 100 times more active against Gram-positive bacteria than against Gram-negative bacteria and revealed a bacteriostatic spectrum quite similar to that of penicillin.