Efflux pumps and drug resistance in gram-negative bacteria.

@article{Ma1994EffluxPA,
  title={Efflux pumps and drug resistance in gram-negative bacteria.},
  author={Dejian Ma and David N. Cook and J. E. Hearst and Hiroshi Nikaido},
  journal={Trends in microbiology},
  year={1994},
  volume={2 12},
  pages={489-93}
}
The outer membrane of Gram-negative bacteria can only slow down the influx of lipophilic inhibitors, and so these bacteria need active efflux pumps of broad specificity to survive. Pumps such as the Escherichia coli Acr system and its homologs make Gram-negative bacteria resistant to dyes, detergents and antibiotics.