Comparison between the BACTEC 9240 and the Pall eBDS system for detection of bacterial platelet concentrate contamination

Only two commercially available automated systems have been cleared by the FDA for screening of bacterial contamination in platelet (PLT) products. These are the Pall eBDS (Pall Corp.), based on measurement of oxygen consumption by contaminant organisms, and the BacT/ALERT (bioMErieux), revealing increasing carbon dioxide concentration due to bacterial growth. The authors compared the performance of the Pall eBDS with the BACTEC 9240 (bioMErieux) in detecting PLT contamination. Serial dilutions of 10 bacterial species frequently associated with PLT contamination were prepared in an apheresis PLT unit per organism. Units were from single donors. After 30 minutes from seeding PLT units, a volume of suspension achieving a final bacterial concentration of 1 to 10 colony-forming units/mL for each unit was inoculated in two Pall bags and a BACTEC bottle, and the same was done after 24 hours from seeding. Measurements were performed at 24 and 30 hours. Significant differences between the two instruments were only found when screening PLT units after 24 hours from seeding. The Pall system showed a higher sensitivity than BACTEC 9240, because it revealed 97 and 98% of positive samples at 24 and 30 hours of incubation, respectively, whereas the second detected 86 and 90% of contaminated products. Significance was lost after 35-hour incubation with the BACTEC 9240. By comparing the two instruments, their performances were found to be comparable; the Pall system appeared as a more suitable method when using 24 to 30 hours as times for readings, but the significant difference was lost after 35-hour incubation.