Detecting bacteria and determining their susceptibility to antibiotics by stochastic confinement in nanoliter droplets using plug-based microfluidics

摘要

This article describes plug-based microfluidic technology that enables rapid detection and drugudsusceptibility screening of bacteria in samples, including complex biological matrices, without preincubation. Unlike conventional bacterial culture and detection methods, which rely on incubationudof a sample to increase the concentration of bacteria to detectable levels, this method confines individual bacteria into droplets nanoliters in volume. When single cells are confined into plugs of smalludvolume such that the loading is less than one bacterium per plug, the detection time is proportionaludto plug volume. Confinement increases cell density and allows released molecules to accumulateudaround the cell, eliminating the pre-incubation step and reducing the time required to detectudthe bacteria. We refer to this approach as ‘stochastic confinement’. Using the microfluidic hybridudmethod, this technology was used to determine the antibiogram – or chart of antibiotic sensitivityud– of methicillin-resistant Staphylococcus aureus (MRSA) to many antibiotics in a single experimentudand to measure the minimal inhibitory concentration (MIC) of the drug cefoxitin (CFX) againstudthis strain. In addition, this technology was used to distinguish between sensitive and resistantudstrains of S. aureus in samples of human blood plasma. High-throughput microfluidic techniquesudcombined with single-cell measurements also enable multiple tests to be performed simultaneouslyudon a single sample containing bacteria. This technology may provide a method of rapidudand effective patient-specific treatment of bacterial infections and could be extended to a varietyudof applications that require multiple functional tests of bacterial samples on reduced timescales.