American Red Cross Biomedical Services, Rockville, MD, USA.
Vox Sang. 2014 Jan;106(1):23-30. doi: 10.1111/vox.12065. Epub 2013 Jul 2.
Platelet septic reactions result from low concentrations of bacteria that escape detection by quality-control BacT/ALERT™ culture testing. We estimate the contamination rate with these bacteria at the time of testing using a mathematical model.
Culture results and reported septic reactions are described for platelets collected between January 2007 and December 2011. Initial positive results with negative confirmatory cultures were reclassified assuming some of the 'unconfirmed positive results' represent collections contaminated with low-concentration, dormant bacteria. A mathematical model based on the probability of the detection of bacteria describes the upper limit of the residual rate of contamination.
The rate of confirmed or unconfirmed positive apheresis platelet donations was 188 per million (1:5317) and 110 per million (1:9124), respectively. The rate of post-transfusion sepsis and reported fatalities per distributed component was 1:106 931 and 1:1 015 843, respectively. A linear decrease in unconfirmed positive Bacillus spp. cultures most likely reflected diminishing environmental contamination over time. The remaining unconfirmed positive results identified similar bacteria species as those associated with septic reactions. Assuming that these represent contamination of the collection with low-concentration, dormant bacteria, the model identified a residual contamination of 3524-204 per million (1:284-1:4902) for collections contaminated with 1-20 bacteria, respectively.
Greater than 99·5% of collections contain no viable, aerobic bacteria in solution at the time of early culture testing. For every confirmed positive contaminated collection detected, there are at most 19 collections with low concentrations of dormant bacteria that are not readily detected by early BacT/ALERT™ culture.
血小板脓毒反应是由低浓度细菌引起的，这些细菌逃脱了质量控制 BacT/ALERT™ 培养检测的检测。我们使用数学模型估计在检测时这些细菌的污染率。
描述了 2007 年 1 月至 2011 年 12 月期间采集的血小板的培养结果和报告的脓毒反应。对初始阳性但阴性确认培养的结果进行重新分类，假设一些“未确认阳性结果”代表采集物受到低浓度休眠细菌的污染。基于细菌检测概率的数学模型描述了残留污染率的上限。
确认或未确认阳性单采血小板捐赠的比率分别为 188/百万（1:5317）和 110/百万（1:9124）。每分发一份成分的输血后脓毒症和报告的死亡率分别为 1:106931 和 1:1015843。未确认阳性芽孢杆菌培养物的线性减少很可能反映了随着时间的推移环境污染的减少。剩余的未确认阳性结果鉴定出与脓毒反应相关的类似细菌。假设这些代表了采集物与低浓度休眠细菌的污染，那么模型确定了污染程度为 1-20 个细菌的采集物的残留污染率分别为 3524-204/百万（1:284-1:4902）。
在早期培养检测时，超过 99.5%的采集物中没有活的需氧细菌。对于每一个检测到的被污染的阳性样本，最多有 19 个样本含有不易被早期 BacT/ALERT™ 培养检测到的低浓度休眠细菌。
