Combating antibiotic resistance using plant‐derived compounds

Bacteria have steadily developed defenses against antibiotics since the world’s first fleet of antibacterial drugs was introduced. One strategy that bacteria can use to become multi‐drug resistant involves the overexpression of large, membrane‐embedded efflux pumps, such as the AcrAB‐TolC pump found in Escherichia coli (E. coli) and other Gram‐negative bacteria. This large efflux pump gives the bacterium the capability of transporting a wide variety of compounds out of the cell, including antibiotics that we use to combat bacterial infections. Overexpression of efflux pumps has been shown to lead to multidrug resistance in clinically important bacterial pathogens. Here, I have sought to identify novel inhibitors of bacterial efflux pumps by screening methanolic plant extracts for efflux pump inhibitory activity using an ethidium bromide‐based fluorescence assay. I have determined that yerba maté extract causes accumulation of ethidium bromide in live E. coli bacterial cells. To determine the ability of yerba maté extract to cause accumulation of clinically relevant antibiotics, I used growth curve analysis of E. coli in the presence of the plant extract with levofloxacin and carbenicillin. I have concluded that the combination of yerba maté and antibiotics enhances the susceptibility of bacteria. This research could open up a new avenue in the treatment of multi‐drug resistant bacterial infections. Support or Funding Information Clare Boothe Luce Research Scholars Program