Effects of amphiphilic compounds on metabolic and biological activities of Salmonella typhimurium.

The effect of two quaternary ammonium salts, (1-methyldodecyl)trimethylammonium bromide (ATDBr) and tetramethylammonium bromide (TMABr), as well as that of two amine oxides, (1-methyldodecyl)dimethylamine oxide (ATDNO) and trimethylamine oxid (TMANO), on both metabolic and biological activities of a S. typhimurium strain isolated from nosocomial infection were studied. The compounds with long alkyl chain in the molecule (ATDBr, ATDNO) affected the growth, synthesis of biomacromolecules (DNA, RNA, proteins) and respiration. The compounds lacking the alkyl chain (TMABr, TMANO) were ineffective with exception of the endogenous respiration that they inhibited in a less degree in the highest concentrations tested. The highest inhibition of respiration was evoked by ATDBr and ATDNO in the presence of pyruvate as an exogenous carbon substrate. The sub-MICs of quaternary ammonium salts induced a prophage of the lysogenic S. typhimurium strain, amine oxides were ineffective. The tested compounds decreased at one-fourth of the MICs the permeability reaction. The results showed that both physiologic and metabolic processes were inhibited in dependence on the length of the alkyl chain, however, amine oxides were less effective in biological activities.