SUPPRESSION OF VIRULENCE FACTORS OF PSEUDOMONAS-AERUGINOSA BY SUBINHIBITORY CONCENTRATIONS OF QUATERNARY AMMONIUM-SALTS

The effect of subinhibitory concentrations (sub-MICs) of two homologou s series of ''soft'' quaternary ammonium salts (QATs) upon the express ion of phospholipase C (Pseudomonas aeruginosa strain 72/92), elastase , proteinase and permeability activity (P. aeruginosa 9/92) was studie d. Both strains were isolated from the patients suffering from nosocom ial infections. Phospholipase C was the most markedly inhibited enzyme . The inhibitory effect was directly proportional to the concentration of substances but the degree of inhibition in the two homologous seri es was different. In the second strain of P. aeruginosa its production of elastase, permeability factor and mainly its proteinase activity w ere less affected by the series of tested QATs. A significant inhibiti on of production of these factors was manifested only in higher concen trations particularly by the substances with longer alkyls. The effect s of QATs on the production of virulence factors could be attributed t o their influence on the metabolic activity of organisms.