Biophysical Society Thematic Meeting - November 16-20, 2015

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 1 , Alissa Myrick 2 , Eric Rubin 2 , Frederick Balagadde 1 . 1 KwaZulu-Natal Research Institute for TB and HIV, Durban, KwaZulu-Natal, South Africa, 2 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 (M.tb) 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 M.tb efflux pump. By conditionally expressing M.tb pumps in 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— an M.tb multidrug 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.

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