Developing a microfluidic device for detecting antibiotic tolerance in bacteria
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Abstract
Overuse and inappropriate prescription of antibiotics has led to the emergence and spread of antimicrobial resistance. While resistant bacteria have inbuilt mechanisms to render antibiotics ineffective, antibiotic tolerance is a survival strategy seen in genetically susceptible bacterial strains. Bacteria exhibiting the tolerance phenotype adopt a dormant state and are able to survive the action of antibiotics that require active growth for killing. This allows tolerant strains to survive intermittent antibiotic exposure and has been shown to facilitate the development of full-blown resistance. To minimize the development of resistance, it is crucial to test for and identify tolerant bacteria in the clinic so that appropriate antibiotic therapy is dispensed. Current methods to evaluate tolerance are based on bacterial growth, and the long incubation periods make them unfit in clinical settings. To solve this issue, this thesis was aimed at developing a microfluidic device that can detect tolerance in E. coli in a span of 2 to 3 hours by monitoring viability of adherent cells at the single cell level. First, susceptibilities of the bacterial strains used were determined via minimal inhibitory concentration (MIC) assays. Then, tolerance was determined by estimating the minimum duration for killing 99% bacteria (MDK99) measurements. Finally, experiments on the microfluidic device were performed to check whether tolerance can be detected, and whether the readout correlated with tolerance measurements from the MDK99 tests.