An Integrated Microfluidic System for Fast Isolation of Bacteria in Human Whole Blood for Diagnosis of Sepsis

Rapid diagnosis of sepsis assists clinicians to initiate timely antibiotic therapy and therefore reduce mortality of bacterial infections. In this work, we presented an integrated microfluidic system for fast isolation of bacteria for both gram-positive and gram-negative bacteria directly from human whole blood, which will be crucial in the detection of sepsis. First, a deterministic lateral displacement (DLD) device was used for sample pretreatment of whole blood, which performed continuous separation of leukocytes, erythrocytes and bacteria. With this approach, most of the blood cells were removed while bacteria and platelets were collected. Then the isolated bacteria were captured with magnetic beads surface-coated with flexible neck regions of mannose-binding lectin (FcMBL) using a new 3D micromixer. The entire process including sample pretreatment and bacteria isolation could be completed on an integrated microfluidic system within 2 hours, which is significantly less than the one for the traditional method (i.e. 3 days). This is the first time that an integrated microfluidic system capable of detecting bacteria by using FcMBL was reported, which may provide a promising way to diagnose sepsis.