SILICON DIFFRACTION GRATINGS FOR REAL-TIME EVALUATION OF ANTIBIOTIC SUSCEPTIBILITY

With global, widespread antibiotic resistance becoming increasingly detrimental to society, it is necessary to improve the methods for determining the best antibiotic drug for use in clinical practice, namely antibiotic susceptibility testing (AST). We have designed and fabricated two-dimensional, photonic phase gratings consisting of silicon micropillar arrays that are biochemically functionalized to provide a preferable solid-liquid interface for bacteria growth. We harness the photonic properties of these microstructures and by real-time monitoring of their reflectance spectra, we can track the state of the bacteria (e.g., growth or lysis) over time within the silicon substrates. In doing so, we can determine the minimum inhibitory concentration of antibiotics needed to stop an infection and determine the SIR (Susceptible-Intermediate-Resistant) profiles of the bacteria towards various antibiotics. Thus, we have developed an AST assay geared towards urinary tract infections that takes less than 3 hours to perform using minimal volumes and has been verified in comparison to the gold standard of broth microdilution testing and the state-of-the-art, automated microbial AST testing system.