Department of Chemical Engineering, Brigham Young University, Provo, Utah, USA.
Biotechnol Prog. 2020 Nov;36(6):e3056. doi: 10.1002/btpr.3056. Epub 2020 Aug 21.
Bacteria must be separated from septic whole blood in preparation for rapid antibiotic susceptibility tests. This work improves upon past work isolating bacteria from whole blood by exploring an important experimental factor: Whole blood dilution. Herein, we use the continuity equation to model red blood cell sedimentation and show that overall spinning time decreases as the blood is diluted. We found that the bacteria can also be captured more efficiently from diluted blood, up to approximately 68 ± 8% recovery (95% confidence interval). However, diluting blood both requires and creates extra fluid that end users must handle; an optimal dilution, which maximizes bacteria recovery and minimizes waste, was found to scale with the square root of the whole blood hematocrit. This work also explores a hypothesis that plasma backflow, which occurs as red cells move radially outward, causes bacterial enrichment in the supernatant plasma with an impact proportional to the plasma backflow velocity. Bacteria experiments carried out with diluted blood demonstrate such bacterial enrichment, but not in the hypothesized manner as enrichment occurred only in undiluted blood samples at physiological hematocrit.
为了准备快速抗生素药敏试验，必须将细菌与感染性全血分离。这项工作通过探索一个重要的实验因素——全血稀释，改进了从全血中分离细菌的以往工作。在此，我们使用连续方程来模拟红细胞沉降，并表明随着血液的稀释，整体旋转时间会减少。我们发现，从稀释的血液中也可以更有效地捕获细菌，回收率最高可达约 68±8%（95%置信区间）。然而，稀释血液既需要也会产生额外的液体，最终用户必须处理；发现一种最佳的稀释方法，可以最大限度地提高细菌回收率并最大限度地减少浪费，这种方法与全血血细胞比容的平方根成正比。这项工作还探讨了一个假设，即当红细胞径向向外移动时会发生血浆回流，这会导致细菌在上清血浆中富集，其影响与血浆回流速度成正比。用稀释血液进行的细菌实验证明了这种细菌富集，但不是以假设的方式发生，因为仅在生理血细胞比容的未稀释血液样本中才会发生富集。
