An integrated microfluidic system for early detection of sepsis-inducing bacteria

Since early diagnosis of sepsis may assist clinicians in initiating timely, effective, and prognosis-improving antibiotic therapy, we developed an integrated microfluidic chip (IMC) for rapid isolation of both Gram-positive and Gram-negative bacteria from blood. The device comprised a membrane-based filtration module (90 min operating time), a bacteria-capturing module using a micro-mixer containing magnetic beads coated with "flexible neck" regions of mannose-binding lectin proteins for bacteria capture (20 min), and a miniature polymerase chain reaction (PCR) module for bacteria identification (90 min via TaqMan (R) probe technology). The filter separated all white blood cells and 99.5% of red blood cells from bacteria, which were captured at rates approaching 85%. The PCR assay's limit of detection was 5 colony-forming units (CFU) per reaction, and the entire process was completed in only 4 h. Since this is far less than that for culture-based approaches, this IMC may serve as a promising device for detection of sepsis.