A Comparison of the BacT/ALERT Results from Plateletpheresis Units Collected Using Baxter Amicus and Gambro Trima.
Authors: Jacobson Jessica L. , O’Brien Teri , Strauss Donna 
Published: October 2019

Introduction: Septic reactions due to bacterially contaminated platelets are the most frequent transfusion-associated infectious risk in the USA today. Bacterial contamination of platelets has been estimated to occur at an incidence of 1:1000 to 1:3000. Diversion technology has been utilized to reduce the risk due to skin contaminants. Single needle Amicus (SNA) and Trima have complete diversion of the first 50 ml of donor blood. Double needle Amicus (DNA) collections, which constitute roughly 75% of our center’s Amicus collections, on the other hand, have diversion on only one of the two needles. The impact of this difference on the true positive (TP) BacT/ALERT rate was evaluated.

Methods: 4 ml aliquots were taken from the parent bag and inoculated into aerobic (BPA) bottles and for 7-day Trima SDPs also into anaerobic (BPN) bottles between 24–36 hours after collection and were monitored using the BacT/ALERT for the life of the product. Any bottle that became positive was sent along with the platelet product for confirmatory gram stain, culture, and identification. The true positive units were then analyzed based on the apheresis collection technology.

Results: During the period from 10-13-03 to 7-31-06, 124,639 SDP samples were processed. Approximately 62,450 of the SDP samples were from Trima, 46,670 were from DNA, and 15,520 were from SNA. 16 (0.01%) TPs were identified. 4 (0.006%) of the TP units were collected on Trima. 7 (0.015%) of the TPs were from DNA collections. 5 (0.035%) of the TPs were from SNA. 1 in 15,625 Trima, 1 in 6,667 DNA, and 1 in 3,125 SNA collections were found to be truly bacterially contaminated. All but one of the organisms identified from both the BacT bottle and the SDP have been aerobic. One obligate anaerobe was identified from both the anaerobic bottle of a 7-day SDP and the SDP. All organisms identified have been reported as possible skin contaminants.

Conclusions: The incomplete diversion in double needle Amicus collections does not result in a higher rate of bacterially contaminated SDPs than does single needle Amicus (p-value=0.18). Trima collections are statistically less likely to yield a contaminated SDP than are Amicus collections (p-value=0.035). Given that Trima collections also are statistically less likely than single needle Amicus collections (p-value=0.007) to result in a true positive, diversion alone is not the complete explanation for this difference. 1 out of 7,692 SDP collections resulted in a true positive. The higher incidence of TPs found from single needle Amicus collections may have been due to chance given the overall small number of TPs identified in from both Trima and single needle Amicus collections.

True Positive SDP Collections (10-13-03 to 7-31-06) Plateletpheresis Technology Used Number of Needles Number of Hours to BacT Detection Organism Identified Full Diversion of Skin Plug Amicus 2 10.6 Beta-hemolytic Streptococcus, Group C No Trima 1 10.4 Streptococcus mitis Yes Amicus 2 62.4 Streptococcus pyogenes No Amicus 1 4.5 Bacillus Yes Trima 1 16.9 Staphylococcus Yes Amicus 1 16.0 Staphylococcus Yes Amicus 1 10.5 Streptococcus mitis Yes Trima 1 10.5 Streptococcus viridans & bovis Yes Trima 1 108 Proprionibacterium acnes Yes Amicus 2 11.3 Serratia marscens No Amicus 2 12.5 Streptococcus salivarius No Amicus 1 41.9 Bacillus Yes Amicus 2 8.0 Serratia marscens No Amicus 2 12.6 Streptococcus bovis No Amicus 1 5.8 Bacillus Yes Amicus 2 10.4 Streptococcus bovis No