Sydney Cord Blood Bank, Sydney Children's Hospital, Randwick, NSW, Australia; University of New South Wales, Sydney, NSW, Australia.
Transfusion. 2014 Mar;54(3):550-9. doi: 10.1111/trf.12352. Epub 2013 Jul 28.
Collection and processing of cord blood (CB) is associated with significant risk of contamination; hence standards mandate microbial screening of the final product. The sensitivity of current methods to evaluate the microbial content of CB is unknown, given the small volume tested and reduced sensitivity of pediatric bottles. Hence, this study was undertaken to evaluate an optimal microbial screening method.
CB was collected using a closed system then spiked with organisms at 1 or 10 colony-forming units (CFUs)/mL. Samples were screened using culture bottles (BacT/ALERT, bioMérieux; and BACTEC, Becton Dickinson). Several methods were evaluated with different combinations of inoculated bottles (adult vs. pediatric), sample types (plasma discard, red blood cell [RBC] discard, or final product), and sample volumes.
Of 94 cord blood units (CBUs) spiked with organisms before screening, 81% tested positive for contamination overall. Screening of CB in pediatric bottles resulted in equivalent detection rates on the BacT/ALERT and BACTEC systems (33% at 1 CFU/mL and 73% at 10 CFUs/mL, respectively). However, the pediatric bottle screen only detected 15% of obligate anaerobes. A combined fraction method showed superior detection (71%) compared to the plasma fraction (27%) and resulted in optimal anaerobic detection.
This study demonstrates that the optimal microbial screening method for CB includes testing a combination of discard fractions (plasma and RBCs) in addition to final product using an automated culture system. Inoculating a small sample of final product in a pediatric bottle is suboptimal for microbial detection and may lead to distribution of contaminated CB for transplantation.
脐带血（CB）的采集和处理存在严重的污染风险；因此，标准要求对最终产品进行微生物筛查。鉴于测试的体积较小且儿科瓶的灵敏度降低，目前评估 CB 微生物含量的方法的灵敏度尚不清楚。因此，进行了这项研究以评估最佳的微生物筛选方法。
使用封闭系统采集 CB，然后以 1 或 10 个菌落形成单位（CFU）/mL 的浓度添加生物体。使用培养瓶（BacT/ALERT，bioMérieux；和 BACTEC，Becton Dickinson）对样品进行筛查。评估了几种方法，使用不同组合的接种瓶（成人与儿科）、样品类型（血浆丢弃、红细胞[RBC]丢弃或最终产品）和样品体积。
在筛查前对 94 个含有生物体的脐带血单位（CBU）进行检测，总体上有 81%检测出污染阳性。在儿科瓶中筛查 CB 时，BacT/ALERT 和 BACTEC 系统的检测率相当（分别为 1 CFU/mL 时为 33%，10 CFUs/mL 时为 73%）。然而，儿科瓶筛查仅检测到 15%的专性厌氧菌。与血浆部分（27%）相比，组合分数法的检测效果更好（71%），并可实现最佳的厌氧检测。
本研究表明，CB 的最佳微生物筛选方法包括使用自动化培养系统测试最终产品的组合丢弃部分（血浆和 RBC）以及添加的小样本最终产品。在儿科瓶中接种少量最终产品进行微生物检测是不理想的，可能导致污染的 CB 用于移植。
