The Germicidal Properties of Certain Quarternary Ammonium Salts With Special Reference to Cetyl-Trimethyl-Ammonium Bromide

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Abstract
A study was made of the bactericidal and bacteriostatic properties of the homologous series of quaternary ammonium salts derived from tetramethyl ammonium bromide. Bactericidal properties became evident when one methyl group was replaced by a nonyl group. Further increase in the chain length produced compounds of high germicidal potency with a definite maximum for cetyl-trimethyl-ammonium bromide. The effect of pH, temp., and the inhibitory effect of serum on the bactericidal and bacteriostatic properties of this compound was studied in more detail. The bactericidal potency of this compound increases considerably with increasing pH. At pH 8 its phenol coeff. for Staphylo-coccus aureus at 37[degree]C was found to be 1,200. When added to nutrient broth, 3 [gamma] per ml will prevent growth of S. aureus. Gram-positive and Gram-negative spp. are equally affected. In the presence of serum a considerable part of the germicidal potency is lost. Comparison of its potency with that of a series of commonly used disinfectants shows that this compound is one of the outstanding bactericidal and bacteriostatic agents.