den Hertog A L, Klatser P R, Anthony R M
KIT Biomedical Research, Royal Tropical Institute, Amsterdam, The Netherlands.
Int J Tuberc Lung Dis. 2009 Apr;13(4):466-71.
A tuberculosis (TB) research laboratory in the Netherlands.
The concentration of Mycobacterium tuberculosis cells from sputum is almost universally performed by centrifugation after chemical liquefaction. These methods are thus dependent on the effective sedimentation of mycobacterial cells, and the buoyant density of these cells relative to sputum is therefore of critical importance.
We cultured M. tuberculosis in different systems and measured their buoyant density. We also calculated the centrifuge times and speeds needed to effectively pellet the mycobacteria.
In contrast to earlier reports, we were unable to identify cells with a buoyant density <1 g/cm(3). The measured buoyant density of the cells ranged from 1.13 to 1.02 g/cm(3), and we suspect that the less dense cells are more likely to reflect clinically derived mycobacterial cells.
Based on our results, this means that for effective sedimentation in a typical universal centrifuge, centrifugation for 22 min at 3200 x g would be required. A limitation of this study is that cultured M. tuberculosis was studied. The data from this study should be confirmed in clinical samples. However, based on our results, centrifugation at lower speed for less time is unlikely to result in effective recovery.
荷兰的一家结核病研究实验室。
痰液中结核分枝杆菌细胞的浓度几乎普遍通过化学液化后离心来测定。因此，这些方法依赖于分枝杆菌细胞的有效沉降，而这些细胞相对于痰液的浮力密度至关重要。
我们在不同系统中培养结核分枝杆菌并测量其浮力密度。我们还计算了有效沉淀分枝杆菌所需的离心时间和速度。
与早期报告相反，我们无法鉴定出浮力密度<1 g/cm³的细胞。所测细胞的浮力密度范围为1.13至1.02 g/cm³，我们怀疑密度较小的细胞更可能反映临床来源的分枝杆菌细胞。
基于我们的结果，这意味着在典型的通用离心机中进行有效沉降时，需要在3200×g下离心22分钟。本研究的一个局限性是研究的是培养的结核分枝杆菌。本研究的数据应在临床样本中得到证实。然而，根据我们的结果，以较低速度离心较短时间不太可能实现有效回收。
