Abstract

Sepsis is a severe blood infection caused by bacteria entering the blood stream. Sepsis caused by antibiotic resistant bacteria is very dangerous with a high mortality rate. The current clinical diagnostic methods for sepsis require culturing the blood sample prior to other steps of the diagnosis procedure. Culturing the blood samples is a time-consuming step which increases the time required for the diagnostic procedure. Considering the fact that the mortality rate of the sepsis increases as time passes, it is essential to find methods for sepsis diagnosis that do not require culturing the samples. The first step of a new diagnostic method for antibiotic resistant sepsis, we have developed a new method for rapid separation of the bacteria from whole human blood based on centrifugal force. Density and size differences between blood cells and bacteria lead to different sedimentation velocities for each of these cells and microorganisms in a centrifugal field. Spinning blood inoculated with bacteria in our designed hollow disks at the specified speed for a designated period of time creates fairly well-separated layers of blood cells and plasma. Red and white cells have higher sedimentation velocities due to higher densities or larger sizes compared to bacteria, forming a region of dense cells close to the wall of the spinning disk. Bacteria sediment slower than red and white cells, moving to and remaining in plasma. By carefully slowing the spinning speed after separation, we are able to avoid remixing of the blood cell layer and bacteria, thus keeping the bacteria separated from rest of the blood cells. This thesis involves the experimental methods for increasing the recovery of the bacteria from human blood by mechanical and chemical methods. It also explains the theory behind the separation technique used.

Degree

College and Department

Ira A. Fulton College of Engineering and Technology; Chemical Engineering

Rights

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