(229au) Effect of Spinning Time and Speed on Separation of Bacteria from Blood for Microfluidic Identification of Bacteria

Bacterial infections in the blood stream (sepsis) can cause severe illness and death if untreated. Even more dangerous is sepsis caused by antibiotic resistant bacteria, which in some cases has a 50% mortality rate. Current clinical methods to diagnose the microorganism and its antimicrobial resistance profile involve culturing the blood, which adds many hours of a time-consuming step in the diagnosis procedure. Considering the fact that the situation of the patient will worsen as the time passes, it is crucial to develop fast diagnosis techniques. The first step in rapid diagnosis using a microfluidic system is to separate the bacteria from the blood. Spinning the blood sample in a hollow disk will produce a centrifugal force acting on all the particles present, including blood cells and bacteria. The difference between the size and density of the bacteria and the blood cells will cause these components to move with different sedimentation velocities. If spinning speed and time are optimized, cells will sediment more quickly than the bacteria, the majority of which will remain in the plasma. This will lead to rapid and practical separation of the bacteria from blood cells. We have conducted experiments using human blood spiked with E. coli spinning in a hollow disk. By varying the spinning time and speed, we have been able to optimize the separation of the bacteria from blood and recover about 50 percent of the bacteria spiked in blood within minutes, which is sufficient for identification. This is the first and perhaps most important step in rapidly identifying the antibiotic resistance of organisms in sepsis. The separated bacteria are injected into a microfluidic system employing genomic identification processes.