Broad-specificity efflux pumps and their role in multidrug resistance of Gram-negative bacteria

FEMS Microbiol Rev. 2012 Mar;36(2):340-63. doi: 10.1111/j.1574-6976.2011.00290.x. Epub 2011 Jul 29.


Antibiotic resistance mechanisms reported in Gram-negative bacteria are causing a worldwide health problem. The continuous dissemination of 'multidrug-resistant' (MDR) bacteria drastically reduces the efficacy of our antibiotic 'arsenal' and consequently increases the frequency of therapeutic failure. In MDR bacteria, the overexpression of efflux pumps that expel structurally unrelated drugs contributes to the reduced susceptibility by decreasing the intracellular concentration of antibiotics. During the last decade, several clinical data have indicated an increasing involvement of efflux pumps in the emergence and dissemination of resistant Gram-negative bacteria. It is necessary to clearly define the molecular, functional and genetic bases of the efflux pump in order to understand the translocation of antibiotic molecules through the efflux transporter. The recent investigation on the efflux pump AcrB at its structural and physiological levels, including the identification of drug affinity sites and kinetic parameters for various antibiotics, may pave the way towards the rational development of an improved new generation of antibacterial agents as well as efflux inhibitors in order to efficiently combat efflux-based resistance mechanisms.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Animals
  • Anti-Bacterial Agents / metabolism
  • Anti-Bacterial Agents / pharmacology*
  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism*
  • Drug Resistance, Multiple, Bacterial*
  • Gram-Negative Bacteria / drug effects
  • Gram-Negative Bacteria / genetics
  • Gram-Negative Bacteria / metabolism*
  • Gram-Negative Bacterial Infections / drug therapy
  • Gram-Negative Bacterial Infections / microbiology*
  • Humans
  • Membrane Transport Proteins / genetics
  • Membrane Transport Proteins / metabolism*


  • Anti-Bacterial Agents
  • Bacterial Proteins
  • Membrane Transport Proteins