Efflux pumps mediating antibiotic resistance

These mechanisms are of considerable microbiological and biochemical interest, although not all of the above agents find current use as biocides. The plasmid-mediated efflux pumps are particularly important, since efflux is one means whereby acquired resistance to antibiotics occurs (see earlier) and can be a mechanism of resistance to some clinically useful biocides (see later). No efflux pump comparable to those described for arsenate and cadmium [212] has yet been detected in silver-resistant bacteria [213] however, an up-to-date assessment of this subject is available [212]. 

Plasmid-mediated resistance to tetracyclines is widespread. Tetracycline-resistant organisms show decreased intracellular accumulation of the drugs. Resistance mechanisms include decreased activity of the uptake systems and the development of mechanisms (efflux pumps) for active extrusion of tetracyclines. Plasmids that include genes involved in the production of efflux pumps for tetracyclines commonly include resistance genes for multiple antibiotics. 

Spratt BG (1994) Resistance to antibiotics mediated by target alterations. Sdence 264 388-393 Stavri M, Piddock LJV, Gibbons S (2007) Bacterial efflux pump inhibitors from natural sources. J Antimicrob Chemother 59 1247-1260... 

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