EFFECT OF QUATERNARY AMMONIUM-SALTS AND AMINE OXIDES ON PSEUDOMONAS-AERUGINOSA

Two quaternary ammonium salts, viz (1-methyldodecyl) trimethylammonium bromide (ATDBr) and tetramethylammonium bromide (TMABr), as well as t wo amine oxides, (1-methyldodecyl)dimethylamine oxide (ATDNO) and trim ethylamine oxide (TMANO), were tested for their inhibitory activity on a Pseudomonas aeruginosa strain isolated from nosocomial infections. Only those compounds with long alkyl chains in their molecules (ATDBr and ATDNO) showed antimicrobial efficacy. In subinhibitory concentrati ons both compounds inhibited incorporation of [C-14]-adenine and [C-14 ]-leucine as precursors of macromolecular biosynthesis. Endogenous res piration of the cells was more sensitive to both agents than the respi ration of various substrates. Among the virulence factors only the pro duction of phospholipase C was inhibited by sub-MICs, while the activi ties of elastase and proteinase were stimulated until the inhibitory c oncentrations were reached. The short-chain analogues TMABr and TMANO did not show these effects. It is suggested that the production of vir ulence factors is affected by amphiphilic compounds due to their antim icrobial activity.