When is the best time for QC testing of platelets for bacteria? Currently the most commonly used strategy is pre-storage testing, in which samples are taken early in platelet unit life, usually 24 hours after collection, and tested by methods that attempt to predict future bacterial growth. An alternate approach is to also test post-storage close to the time of transfusion after the bacteria have proliferated if they are going to do so.Watch Demo
The biological variability of bacterial growth poses unique hurdles for pre-storage QC testing with methods such as culture. This is because when samples are taken for testing, typically 24 hours after the platelets are collected, the bacteria have often not yet exited their lag phase and begun log phase growth, resulting in the potential for false negative results. When this occurs, those bacteria may enter log phase growth in the platelet unit after sampling resulting a highly contaminated unit being allowed into the inventory for transfusion. False negative results can also occur when the units are transfused before the culture result turns positive as it can sometimes take 2 to 3 days before results are available.
Additionally, pre-storage QC testing at Day 1 followed by a 1 to 2 day turnaround time for culture results can result in quarantines and increased outdating, all of which can seriously complicate platelet inventory management.
Post-storage QC testing may offer the potential to address the challenge of biological variability in bacterial growth patterns. By also testing closer to the time of platelet issue for transfusion there is an opportunity to detect both fast growing as well as slow growing bacteria. This strategy could potentially avoid culture false negatives while avoiding quarantines or call-backs due to delayed results, as well as inventory disruptions. This strategy is highly dependent upon a test with unique capabilities; capabilities that have proven elusive to achieve until now with the advent of Verax’s PGD technology.