Single Cell Antimicrobial Susceptibility Testing Using Drop-Based Microfluidics

Antimicrobial resistance (AMR) poses a critical global health threat, creating a need for rapid identification of effective drug treatments. The current gold standard for antimicrobial susceptibility testing (AST) is the minimum inhibitory concentration (MIC), the lowest concentration of antibiotic required to prevent microbial growth. The limitations of this test include long time to results and limited detection of resistant outlier cells. Drop-based microfluidics enables rapid and sensitive detection of single cells and the early detection of bacterial divisions, significantly reducing result turnaround time compared to traditional methods. Individual bacterial cells are first encapsulated in drops containing growth medium and antibiotics. Fluorescence signals are then detected within individual drops corresponding to cell growth using a custom-built high-speed fluorescent microscope. Drops can be sorted using dielectrophoresis for further downstream analysis with a sensitivity of 0.96 and specificity of 0.90. This work establishes a methodology for analyzing single cell MIC in high-throughput within 1-3 hours. The development of a diagnostic platform that can provide rapid, individualized results will be a powerful tool in addressing the threat of AMR.