Biophysical Society Thematic Meeting

Biophysics in the Understanding, Diagnosis, and Treatment of Infectious Diseases Poster Abstracts

23-POS

Board 23

Antibiotic Resistance and its Cost in E. Coli Cells Expressing Tap—A Multidrug Efflux

Pump of Mycobacterium Tuberculosis

Jared Mackenzie

, Alissa Myrick

, Eric Rubin

, Frederick Balagadde

KwaZulu-Natal Research Institute for TB and HIV, Durban, KwaZulu-Natal, South

Africa,

Harvard School of Public Health, Boston, MA, USA.

Drug resistance is a serious global health problem, with 2 million people each year being

infected with drug resistant bacteria in the US alone. It is believed that efflux pumps are systems

that Tuberculosis microbes as well as other microbes use to survive antibiotics by extruding the

drug molecules that enter the bacteria. To date, the study of the

Mycobacterium tuberculosis

)

efflux system is plagued with problems such as functional redundancy that have frustrated

efforts to determine the functions of any single pump. We propose a new approach to

discovering the role of each

efflux pump. By conditionally expressing

pumps

E.coli

strains that are deficient in transporter proteins and highly sensitive to drugs, we can

characterize each mycobacterial efflux pump in terms of substrate specificity, cognate inhibitors

and efflux capacity. This is done through the use of Microfluidics and novel microchemostat

technology. This technology involves the use of a microfluidic chip that can grow bacterial cells

in perpetuity, allowing us to systematically monitor the long-term dynamics of each tuberculosis

efflux pump, with the ability to resolve gene expression differences between individual cells.

Using these

E.coli

constructs, we have characterized the Tap-like efflux pump Rv1258—

ultidrug efflux pump. Cells expressing Tap had increased resistance to streptomycin

and gentamicin relative to wild type cells, with a greater level of resistance observed with the

latter antibiotic. Our results also indicate that whilst conferring increased resistance to

antibiotics, efflux pump expression comes at a fitness cost to the bacteria. This fitness cost

induces a non-growth state that may also independently confer tolerance to antibiotics that

require active microbial growth to be potent.