Knock‐out of multidrug efflux pump MexXY‐OprM results in increased susceptibility to antimicrobial peptides in Pseudomonas aeruginosa

Abstract Multidrug efflux systems of the resistance‐nodulation‐cell division family play a crucial role in resistance of Pseudomonas aeruginosa to a large variety of antibiotics. Here, we investigated the role of clinically relevant efflux pumps MexAB − OprM, MexCD − OprJ, and MexXY − OprM in resistance against different cationic antimicrobial peptides (AMPs). Our results indicate that a knock‐out in efflux pump MexXY‐OprM increased susceptibility to some AMPs by two‐ to eightfold. Our data suggest a contribution of MexXY‐OprM in resistance to certain AMPs in P. aeruginosa , which should be considered in the future development of new and highly active antimicrobial peptides to fight multidrug resistant infections.