TABLE 3.

Characteristics of RND efflux pumps in P. aeruginosa

OperonComponentFunctionaRegulatoreSubstrate(s)
PrimarybSecondarycAntibioticsAdditional compounds
mexAB-oprMMexAMFPMexRNalCFluoroquinolones, β-lactams, β-lactamase inhibitors, tetracyclines, chloramphenicol, macrolides, novobiocin, trimethoprim, sulfonamidesBiocides (e.g., triclosan), detergents, dyes, HSL,f aromatic hydrocarbons
MexBRNDNalD
OprMOMF
mexCD-oprJMexCMFPNfxBFluoroquinolones, β-lactams, tetracycline, chloramphenicol, macrolides, trimethoprim, novobiocinBiocides (e.g., triclosan), detergents, dyes, aromatic hydrocarbons
MexDRND
OprJOMF
mexEF-oprNMexEMFPMexTMexSFluoroquinolones, chloramphenicol, trimethoprimBiocides (e.g., triclosan), aromatic hydrocarbons
MexFRNDMvaT
OprNOMF
mexXYMexXMFPMexZFluoroquinolones, β-lactams, tetracycline, aminoglycosides, macrolides, chloramphenicol
MexYRND
OprM/Opm-dOMF
mexJKMexJMFPMexLTetracycline, erythromycinBiocides (e.g., triclosan)
MexKRND
OprM/OpmHOMF
mexGHI-opmDMexG?SoxRFluoroquinolonesVanadium
MexHMFP
MexIRND
OpmDOMF
mexVWMexVMFPFluoroquinolones, tetracycline, chloramphenicol, erythromycin
MexWRND
OprMOMF
mexPQ-opmEMexPMFPFluoroquinolones, tetracycline, chloramphenicol, macrolides
MexQRND
OpmEOMF
mexMNMexMMFPChloramphenicol, thiamphenicol
MexNRND
OprMOMF
triABCTriAMFPTriclosan
TriBMFP
TriCRND
OpmHOMF
  • a MFP, membrane fusion protein; RND, resistance-nodulation-division transporter; OMF, outer membrane factor; ?, encodes a protein of unknown function.

  • b Regulatory proteins that directly control expression of the efflux operons.

  • c Proteins that indirectly activate operon expression when mutated.

  • d MexXY may utilize OpmB, OpmG, OpmH, and/or OmpI as OMFs.

  • e —, not identified.

  • f HSL, homoserine lactones.