Honors Theses


Matthew Lopper



Publication Date


Document Type

Honors Thesis


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). This large efflux pump gives the bacterium the capability of transporting antibiotics out of the cell. Multi-drug resistant bacteria cells have been shown to overexpress efflux pumps which allows them to pump out antibiotics so that the remaining concentration of antibiotics within the cell is no longer lethal, rendering our antibiotics ineffective against these bacteria. My goal is to find a plant extract that can inhibit the efflux pumps of E. coli which would make antibiotics effective against the bacteria. 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 presence of yerba maté has an antibacterial effect on the bacteria. Further research should be done to determine a lethal dosage of the extract as well as the effect of the extract on other types of cells. This research could open up a new avenue in the treatment of multi-drug resistant bacterial infections.

Permission Statement

This item is protected by copyright law (Title 17, U.S. Code) and may only be used for noncommercial, educational, and scholarly purposes.


Undergraduate research

Embargoed until Sunday, June 23, 2120