CUR - The Council on Undergraduate Research

Identifying Collateral Sensitivity Networks and Associated Genetic Markers in Burkholderia Species

Enosh Ishman, Dr. Todd Steck, Department of Biological Sciences, University of North Carolina at Charlotte, 9201 University City Blvd, Charlotte, NC 28223

Antibiotic collateral sensitivity, seen when a drug-resistant organism becomes sensitive to an alternate drug, might be used to develop therapies to treat chronic bacterial lung infections in cystic fibrosis patients. Our purpose is to characterize how common this phenomenon is and to identify genes or specific mutations involved in collateral sensitivity (CS) in the study organism Burkholderia multivorans. Methods involve each strain being swabbed onto growth agar to create a lawn of bacteria, then adding antibiotic disks to the center of the Petri plate. After incubation to promote bacterial growth, the killing area caused by antibiotic diffusing from the disk is measured. This zone reflects the resistance category of the plated bacteria. Resistant bacteria are then tested for collateral sensitivity. If tested positive, an Etest, a strip of paper containing a known gradient of antibiotic concentration, will be used to quantitate the degree of change in antibiotic resistance. The Etest strip is placed on a plate seeded with bacteria, which then grows up to the place on the strip corresponding to the killing of antibiotic concentration. This process of selecting for resistant mutants, and identifying those that exhibit CS, will continue for multiple generations. The ultimate goal is to identify mutations involved in CS, and confirm involvement of those genes by introducing that mutation into a wild type strain using gene editing techniques.

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