In vitro influence of polyunsaturated fatty acids on nosocomial Pseudomonas aeruginosa: a preliminary report.

Recent evidence derived from a mouse infection model implies an 'anti-infective' role of polyunsaturated fatty acids (PUFAs) which could not be attributed to an alteration of eicosanoid or cytokine biosynthesis provoked by them. In order to investigate that role, seven Pseudomonas aeruginosa nosocomial pathogens were in vitro exposed to 200 and 300 mug/ml of two PUFAs, arachidonic acid (AA) and gamma-linolenic acid (GLA), by performing 43 time-kill curves. Both PUFAs were found to inhibit P. aeruginosa growth as compared to their controls, an effect maximized at 5 h of incubation and minimized at 24 h. The strains that survived after the 24 h AA and GLA exposure were removed from the culture medium with added AA or GLA; half of these strains acquired enormously higher MIC and MBC values to aminoglycosides compared to their relevant controls. The possible mechanism of action of AA and GLA on P. aeruginosa and the clinical relevance of the presented findings is a matter of further research.