Buchanan Clara M, Wood Ryan L, Hoj Taalin R, Alizadeh Mahsa, Bledsoe Colin G, Wood Madison E, McClellan Daniel S, Blanco Rae, Hickey Caroline L, Ravsten Tanner V, Husseini Ghaleb A, Robison Richard A, Pitt William G
Chemical Engineering Department, Brigham Young University, Provo, UT, USA.
Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, USA.
J Microbiol Methods. 2017 Aug;139:48-53. doi: 10.1016/j.mimet.2017.05.004. Epub 2017 May 8.
A rapid and accurate diagnosis of the species and antibiotic resistance of bacteria in septic blood is vital to increase survival rates of patients with bloodstream infections, particularly those with carbapenem-resistant enterobacteriaceae (CRE) infections. The extremely low levels in blood (1 to 100CFU/ml) make rapid diagnosis difficult. In this study, very low concentrations of bacteria (6 to 200CFU/ml) were separated from 7ml of whole blood using rapid sedimentation in a spinning hollow disk that separated plasma from red and white cells, leaving most of the bacteria suspended in the plasma. Following less than a minute of spinning, the disk was slowed, the plasma was recovered, and the bacteria were isolated by vacuum filtration. The filters were grown on nutrient plates to determine the number of bacteria recovered from the blood. Experiments were done without red blood cell (RBC) lysis and with RBC lysis in the recovered plasma. While there was scatter in the data from blood with low bacterial concentrations, the mean average recovery was 69%. The gender of the blood donor made no statistical difference in bacterial recovery. These results show that this rapid technique recovers a significant amount of bacteria from blood containing clinically relevant low levels of bacteria, producing the bacteria in minutes. These bacteria could subsequently be identified by molecular techniques to quickly identify the infectious organism and its resistance profile, thus greatly reducing the time needed to correctly diagnose and treat a blood infection.
快速准确地诊断败血症血液中细菌的种类和抗生素耐药性对于提高血流感染患者，尤其是耐碳青霉烯类肠杆菌科（CRE）感染患者的生存率至关重要。血液中细菌含量极低（1至100CFU/ml）使得快速诊断变得困难。在本研究中，通过在旋转空心盘中快速沉降，从7ml全血中分离出极低浓度的细菌（6至200CFU/ml），该旋转空心盘将血浆与红细胞和白细胞分离，使大多数细菌悬浮在血浆中。旋转不到一分钟后，减慢圆盘转速，回收血浆，并通过真空过滤分离细菌。将滤膜接种在营养平板上以确定从血液中回收的细菌数量。实验分别在未进行红细胞（RBC）裂解和对回收血浆进行RBC裂解的情况下进行。虽然低细菌浓度血液的数据存在离散性，但平均回收率为69%。献血者的性别对细菌回收率没有统计学差异。这些结果表明，这种快速技术能从含有临床相关低水平细菌的血液中回收大量细菌，并在数分钟内获得细菌。随后可通过分子技术鉴定这些细菌，以快速识别感染性生物体及其耐药谱，从而大大缩短正确诊断和治疗血液感染所需的时间。
