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

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.