I've come across some mentions of MDR (Multidrug Resistance) pumps, and MDR pump inhibitors:

I assume there's a reason we're not mixing in Oregon Grape root into our antibiotic cocktails? http://en.wikipedia.org/wiki/Oregon-grape http://www.ncbi.nlm.nih.gov/pmc/articles/PMC26451/ http://www.ncbi.nlm.nih.gov/pubmed/11321580