Triclosan depletes the membrane potential inPseudomonas aeruginosabiofilms inhibiting aminoglycoside induced adaptive resistance
Abstract
Biofilm-based infections are difficult to treat due to their inherent resistance to antibiotic treatment. Discovering new approaches to enhance antibiotic efficacy in biofilms would be highly significant in treating many chronic infections. Exposure to aminoglycosides induces adaptive resistance inPseudomonas aeruginosabiofilms. Adaptive resistance is primarily the result of active antibiotic export by RND-type efflux pumps, which use the proton motive force as an energy source. We show that the protonophore uncoupler triclosan depletes the membrane potential of biofilm growingP. aeruginosa, leading to decreased activity of RND-type efflux pumps. This disruption results in increased intracellular accumulation of tobramycin and enhanced antimicrobial activityin vitro. In addition, we show that triclosan enhances tobramycin effectivenessin vivousing a mouse wound model. Combining triclosan with tobramycin is a new anti-biofilm strategy that targets bacterial energetics, increasing the susceptibility ofP. aeruginosabiofilms to aminoglycosides.
Author summary
Adaptive resistance is a phenotypic response that allowsP. aeruginosato transiently survive aminoglycosides such as tobramycin. To date, few compounds have been identified that target adaptive resistance. Here, we show the protonophore uncoupler triclosan disrupts the membrane potential ofP. aeruginosa. The depletion of the membrane potential reduces efflux pump activity, which is essential for adaptive resistance, leading to increased tobramycin accumulation and a shorter onset of action. Our results demonstrate that in addition to its canonical mechanism inhibiting membrane biosynthesis, triclosan can exert antibacterial properties by functioning as a protonophore that targetsP. aeruginosaenergetics.
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