Bacterial Extraction from Blood through Lysis Filtration and Subsequent Removal from Filter

Blood stream infections (BSIs) are challenging infections to rapidly diagnose. The current clinical diagnostic methods for BSIs require culturing the blood sample prior to identifying the bacteria and any antibiotic resistance the bacteria may contain. Removing the culturing step from the bacterial identification process of a BSI provides a significant reduction in the processing time, but shifts the difficulty from processing time to concentration, since clinical concentration levels can be as low as 10 CFU/mL in blood. This study developed a new method, whole blood filtering, to identify bacteria from a BSI without culturing the bacteria. Filtering whole blood achieved 100% bacterial removal from 5 mLs of whole blood in ~90 s. However, the bacteria were difficult to remove from the filter, leading to further investigation. At a very low bacterial concentration of 200 CFU/mL, a blood lysis solution of 3% Tween 80 followed by a 3% Pluronic F108 backflush solution achieved 60% removal of the bacteria from the filter.