Emergence of resistant Escherichia coli mutants in microfluidic on-chip antibiotic gradients

We used a gradient generator microfluidic device to study the emergence of tolerant and resistant Escherichia coli in ciprofloxacin concentration gradients. Using time-lapse fluorescence microscopy, we observed the population level response to various gradients of ciprofloxacin for up to 72 hours, after which, we performed genomic sequencing to identify key mutations leading to antibiotic resistance.