Author Date


Degree Name



Chemical Engineering


Ira A. Fulton College of Engineering and Technology

Defense Date


Publication Date


First Faculty Advisor

Dr. William G. Pitt

First Faculty Reader

Dr. Bradley C. Bundy

Second Faculty Reader

Dr. Richard Robison

Honors Coordinator

Dr. William G. Pitt


concentrating bacteria, centrifugation, sepsis, blood stream infections


The rapid diagnosis of blood stream infections (BSIs) is limited by the low concentration of bacteria in the blood. Currently, culturing of blood samples is used to increase the concentration of bacteria before the type of bacteria and the best antibiotic to treat the infection can be identified. However, the culturing of blood samples takes tens of hours, and therefore concentrating the bacteria from blood without growth will allow for quicker analysis and is crucial to saving lives. This thesis explored the means of concentrating E. coli suspensions in phosphate buffered saline (PBS), plasma, and simulated blood by centrifuging the E. coli into a smaller volume. An average concentration of 9-fold was accomplished with 1 mL of E. coli suspended in plasma by centrifuging for 10 minutes. A similar process for concentrating E. coli in PBS gave a very poor recovery. By determining the concentration profile of E. coli suspended in PBS, it was determined that 10 µL is the optimum volume to pipette from the bottom of a microcentrifuge tube after centrifuging to achieve the highest bacterial recovery. Concentrating bacteria in simulated blood is much more successful than concentrating bacteria in PBS and the total recovery of E. coli is highest with simulated blood suspension and reverse osmosis (RO) water compared to plasma and PBS suspensions.