Ratnam S, March S B
J Clin Microbiol. 1986 Mar;23(3):582-5. doi: 10.1128/jcm.23.3.582-585.1986.
Optimum relative centrifugal force (RCF) and centrifugation time to concentrate mycobacteria in clinical specimens were determined by processing split samples of sputa and urines containing mycobacteria with combinations of different RCFs and centrifugation times. Although individual test results showed considerable variation in the recovery rates of mycobacteria in the sediment, the data indicated that higher recovery rates occurred as centrifugation speed and time were increased. With a 15- to 20-min centrifugation time, on the average, 67 to 71% of mycobacteria were recovered at an RCF of 2,074 X g, and 76 to 80% were recovered at 3,005 or 3,895 X g at maximum radius. The remainder of mycobacteria was mostly recovered from the supernatant, but culturing of supernatant was not profitable. Increasing RCF had a negligible effect on acid-fast bacillus smear sensitivity. The smear sensitivity for about 25,000 clinical specimens processed with an RCF of 3,800 X g for 20 min was 71% compared with 69% as determined for over 30,000 specimens processed in a similar manner but an RCF of 2,000 X g. An RCF of 3,000 X g applied for 15 min, or an RCF of about 2,000 to 2,500 X g applied for 20 min, is considered adequate to concentrate mycobacteria in clinical specimens.
通过对含有分枝杆菌的痰液和尿液的分割样本采用不同相对离心力（RCF）和离心时间的组合进行处理，确定了临床标本中浓缩分枝杆菌的最佳相对离心力和离心时间。尽管各个测试结果显示沉积物中分枝杆菌的回收率存在相当大的差异，但数据表明，随着离心速度和时间的增加，回收率会更高。在15至20分钟的离心时间下，平均而言，在2074×g的相对离心力下可回收67%至71%的分枝杆菌，在最大半径处3005或3895×g的相对离心力下可回收76%至80%的分枝杆菌。其余的分枝杆菌大多从上清液中回收，但培养上清液并不划算。增加相对离心力对抗酸杆菌涂片敏感性的影响可忽略不计。用3800×g的相对离心力处理20分钟的约25000份临床标本的涂片敏感性为71%，而用类似方式处理但相对离心力为2000×g的30000多份标本的涂片敏感性为69%。3000×g的相对离心力处理15分钟，或约2000至2500×g的相对离心力处理20分钟，被认为足以浓缩临床标本中的分枝杆菌。
