Efflux pumps are a really cool way for bacteria to get rid of harmful substances. Bacteria have used them for a long time, for a lot of different substances. They certainly predate prescription antibiotics by a lot. It’s also good to remember that it was nature, not us, who originally invented antibiotics. Like, if a bacteria gets all up in the face of a fungus, the fungus is going to protect itself.

Many bacteria have these kinds of pumps from long ago, but our over-use of antibiotics just makes them more effective against modern drugs and  more wide spread.

Reygaert (2018) contains an extensive overview of antimicrobial resistance mechanisms, including efflux pumps.

 

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Reygaert (2018) An overview of the antimicrobial resistance mechanisms of bacteria https://doi.org/10.3934/microbiol.2018.3.482